Vacuum pump

Abstract

A vacuum pump comprising: a stator (114) comprising one or more stator walls (122, 124, 126) defining a pump chamber (118); and a heat transfer device (130) coupled to the one or more stator walls (122, 124, 126), the heat transfer device (130) comprising: a heat conductor (126; and a conduit (132) passing through the heat conductor and, in use, a purge gas passing through the conduit, thereby heating the purge gas.

Description

TECHNICAL FIELD

[0001] The present invention relates to vacuum pumps. BACKGROUND

[0002] Vacuum pumps are used in various technical processes to pump process gas out of a process chamber, thereby creating low pressure conditions for the respective process. The process gas can contain by-products of the process. The by-products can progress into the pump chamber of the vacuum pump, where they can solidify or condense. The solidified by-products can settle on surfaces within the pump chamber, such as the inner walls of the pump chamber and the outer peripheral surface of the rotor. The deposited by-products can narrow the gap between the rotor. The deposited by-products can lead to reduced pumping efficiency, bearing damage, and eventually to failure of the vacuum pump.

[0003] It is known to use a purge or flushing gas to prevent or counteract the accumulation of solidified by-products. During operation of the pump, the purge gas can be discharged into the pump chamber via a purge gas line. Preferably, the purge gas is delivered at high speed, for example via a nozzle. The flow of purge gas prevents the settling of solid particles within the pump chamber and helps to transport them out of the pump chamber.

[0004] It is known to use a mechanical booster pump in combination with a vacuum pump. The mechanical booster pump or pumps can be mechanically coupled to the vacuum pump, for example at the inlet of the vacuum pump, such that in operation the mechanical booster pump increases the pressure of the fluid entering the vacuum pump. SUMMARY

[0005] Heating the stator of the vacuum pump can prevent the condensation and deposition of by-products within the pump chamber.

[0006] However, the present inventors have recognized that the introduction of purge gas into the pump chamber can lower the temperature within the pump chamber and / or the temperature of the stator walls, thereby causing condensation of by-products present within the pump chamber. The present inventors have also recognized that pre-heating the purge gas before introducing it into the pump chamber tends to reduce the cooling effect of the introduction of the purge gas, thereby reducing the condensation and deposition of by-products within the pump chamber.

[0007] The present inventors have also recognized that a heat exchanger can be housed in the wall of a pump stator, such as the stator of a booster pump, and can be used to pre-heat the purge gas before it is introduced into the pump chamber of a vacuum pump, for example another pump downstream of the booster pump. The present inventors have also recognized that a heater can also be housed in the wall of a pump stator, such as the stator of a booster pump, and can be used to heat the stator wall, thereby heating the pump chamber of the booster pump and the purge gas flowing through the heat exchanger.

[0008] In a first aspect, there is provided a vacuum pump stator comprising one or more walls defining a pump chamber, and a heat exchanger comprising a conduit passing through at least one of the one or more walls, through which, in use, a purge gas is passed, thereby heating the purge gas.

[0009] The conduit can comprise a conduit inlet and a conduit outlet. The conduit inlet can be located at an outer surface of the one or more walls. The conduit outlet can be located at an outer surface of the one or more walls. The conduit, connected between the conduit inlet and the conduit outlet, can be separated from the pump chamber by at least one of the one or more walls.

[0010] The one or more walls can comprise a first wall, a second wall opposite the first wall, and one or more further walls disposed between the first wall and the second wall. The vacuum pump stator can further comprise a pump chamber inlet defined in the first wall and a pump chamber outlet defined in the second wall. The conduit can be embedded in or integrally formed with the one or more further walls.

[0011] The vacuum pump stator can further comprise one or more heaters configured to heat at least a portion of the one or more walls.

[0012] The one or more heaters can be at least partially embedded in the one or more walls.

[0013] The conduit can be defined by a channel formed on an outer surface of the one or more walls and a cover covering at least a portion of the channel and fixedly attached to the one or more walls.

[0014] The conduit can be a coiled conduit.

[0015] In another aspect, there is provided a vacuum pump comprising a stator according to any preceding aspect, one or more rotors arranged in the pump chamber, and one or more shafts extending at least partially through the pump chamber. The one or more rotors are fixed to a respective one of the one or more shafts.

[0016] In another aspect, there is provided a system comprising a vacuum pump of any preceding aspect, and a purge gas source configured to supply a purge gas into the conduit.

[0017] The pump chamber can comprise a first pump chamber inlet and a first pump chamber outlet. The system can further comprise a further vacuum pump. The further vacuum pump can comprise a further pump chamber. The further pump chamber can comprise a second pump chamber inlet and a second pump chamber outlet. The first pump chamber outlet can be coupled to the second pump chamber inlet such that, in use, fluid is pumped from the pump chamber to the further pump chamber. The heat exchanger can be coupled to the further pump chamber such that, in use, heated purge gas is supplied into the further pump chamber.

[0018] The vacuum pump can be a booster pump.

[0019] In another aspect, there is provided a method comprising: providing a vacuum pump, the vacuum pump being a vacuum pump according to any preceding aspect; pumping a fluid using the vacuum pump, the fluid being pumped through a pump chamber of the vacuum pump; and flowing a purge gas through a conduit of the heat exchanger. Heat is transferred from the one or more walls to the purge gas as the purge gas flows through the conduit, thereby heating the purge gas.

[0020] The purge gas can be nitrogen.

[0021] The method can further comprise heating at least a portion of the one or more walls by one or more heaters.

[0022] The method can further comprise outputting the heated purge gas from the heat exchanger to a further vacuum pump.

[0023] In another aspect, there is provided a vacuum pump comprising a stator and a heat transfer arrangement. The stator comprises one or more stator walls defining a pump chamber. The heat transfer arrangement is coupled to the one or more stator walls. The heat transfer arrangement comprises a heat conductor and a conduit passing through the heat conductor. The conduit is such that, in use, a purge gas passes through the conduit, thereby heating the purge gas.

[0024] The heat transfer arrangement can be attached to (e.g. by fasteners) an outer surface of the one or more stator walls.

[0025] The conduit can comprise a pipe embedded within the heat conductor. The pipe can be partially embedded within the heat conductor, for example the pipe can be press-fitted into a groove formed in a surface of the heat conductor. Alternatively, the pipe can be fully embedded within the heat conductor, for example the pipe can be cast into a solid body of the heat conductor. The pipe can be a stainless steel pipe.

[0026] The heat conductor can be a plate or block of a thermally conductive material, such as a metal. The heat conductor can comprise aluminium, for example the heat conductor can be a plate made substantially of aluminium or an aluminium alloy.

[0027] The conduit can be a coiled, tortuous or serpentine conduit.

[0028] The heat transfer arrangement can further comprise one or more heaters embedded therein. The heaters can be elongate heaters, each contained within a respective aperture passing through the thermally conductive material. The heat transfer arrangement can comprise a plurality of heaters arranged in spaced apart relation to one another. The conduit can be a coiled conduit passing through one or more spaces between the heaters. The one or more heaters and the conduit can be arranged as a common layer or plane within the thermally conductive material. Alternatively, the heaters and the conduit can be arranged in different respective layers or planes within the thermally conductive material, the planes or layers being substantially parallel to one another.

[0029] The heat transfer device can further comprise a further conduit through the thermally conductive body, and in use, a cooling fluid (e.g. water) passes through the further conduit, thereby cooling the thermally conductive body. The further conduit can be a coiled, tortuous or serpentine conduit.

[0030] The heat transfer device can comprise a further conduit through the thermally conductive body, the further conduit being arranged to receive a cooling fluid (and in use can receive a cooling fluid such that the cooling fluid passes through the thermally conductive body to provide cooling thereto). The further conduit can be arranged in the thermally conductive body as a first layer (e.g. substantially in a first plane). The heat transfer device can comprise a plurality of heaters arranged in the thermally conductive body as a second layer (e.g. substantially in a second plane). The second layer can be substantially parallel to the first layer. The conduit can be arranged in the thermally conductive body as a third layer (e.g. substantially in a third plane). The third layer can be substantially parallel to the first layer and the second layer. The third layer can be disposed between the first layer and the second layer. Alternatively, the second layer can be disposed between the first layer and the third layer.

[0031] The conduit can comprise an inlet located at or proximate to a first side of the heat transfer device, and an outlet located at or proximate to a second side of the heat transfer device, the second side being opposite the first side. The first side can correspond to a low vacuum side of the vacuum pump, and the second side can correspond to a high vacuum side of the vacuum pump. Alternatively, the first side can correspond to a high vacuum side of the vacuum pump, and the second side can correspond to a low vacuum side of the vacuum pump. In other words, the stator can comprise a high vacuum end and a low vacuum end, and the conduit can comprise an inlet located at or proximate to one of the high vacuum end or the low vacuum end, and an outlet located at or proximate to the other of the high vacuum end or the low vacuum end.

[0032] In another aspect, there is provided a system comprising a vacuum pump according to any preceding aspect, and a source of purge gas configured to supply purge gas into the conduit.

[0033] In another aspect, there is provided a method comprising: providing a vacuum pump according to any preceding aspect; pumping a fluid using the vacuum pump, the fluid being pumped through a pump chamber of the vacuum pump; and flowing a purge gas through a conduit of a heat transfer device. When the purge gas flows through the conduit, heat is transferred from the stator to the purge gas via the thermally conductive body, thereby heating the purge gas. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a schematic illustration (not to scale) of a vacuum pumping system; Figure 2 is a schematic illustration (not to scale) of an exploded perspective view of a first stator of a first vacuum pump; Figure 3 is a process flow diagram illustrating certain steps of a process performed by a vacuum pumping system; Figure 4 is a schematic illustration (not to scale) showing a perspective view of a vacuum pump including a heat transfer device; Figure 5 and 6 is a schematic illustration (not to scale) showing a heat transfer device; Figure 7 is a schematic illustration (not to scale) showing another heat transfer device; Figure 8 is a schematic illustration (not to scale) showing yet another heat transfer device; and Figure 9 is a schematic illustration (not to scale) showing a cross-section of yet another heat transfer device. DETAILED DESCRIPTION

[0035] It will be appreciated that relative terms such as above and below, horizontal and vertical, top and bottom, front and back, and the like are used herein for ease of reference only to facilitate describing the various figures and that these terms are not intended to be limiting and that any two different directions or positions, etc., can be implemented instead of the true above and below, horizontal and vertical, top and bottom, etc.

[0036] Figure 1 is a schematic illustration (not to scale) of a vacuum pumping system 100.

[0037] The vacuum pumping system 100 includes a facility 101, a first vacuum pump 102, a second vacuum pump 104, and a purge gas source 106.

[0038] The facility 101 can be any suitable type of facility, such as a semiconductor manufacturing facility. The facility 101 is coupled to a vacuum pumping system including the first vacuum pump 102 and the second vacuum pump 104. The vacuum pumping system 100 is configured to establish a vacuum or low pressure environment at the facility 101 by extracting gas (e.g., air or process gas) from the facility 101.

[0039] The first vacuum pump 102 is a mechanical booster pump. The first vacuum pump 102 can be any suitable type of booster pump, such as a Roots-type or Roots vacuum pump. The first vacuum pump 102 can be a positive displacement pump. The first vacuum pump 102 is operably coupled between the facility 101 and the second vacuum pump 104. The first vacuum pump 102 is configured to pump fluid (e.g., gas) out of the facility 101, as indicated by the arrow and reference numeral 108 in Figure 1 The first vacuum pump 102 is also configured to pump the fluid to the second vacuum pump 104 via a fluid line 110, as indicated by the arrow and reference numeral 112 in Figure 1The first vacuum pump 102 is configured to increase the pressure of the pumped fluid entering the second vacuum pump 104. This operation of the first vacuum pump 102 tends to increase the pumping efficiency of the second vacuum pump 104.

[0040] The first vacuum pump 102 includes a first housing or stator 114. The first stator 114 includes one or more walls that define a first fluid inlet 116, a first pump chamber 118, and a first fluid outlet 120.

[0041] In particular, in this embodiment, the first stator 114 includes a first or top wall 122, a second or bottom wall 124 opposite the first wall 122, and one or more additional walls or side walls 126 disposed between the first wall 122 and the second wall 124. The first fluid inlet 116 is formed through the first wall 122. The first fluid outlet 120 is formed through the second wall 124.

[0042] The first vacuum pump 102 also includes a first pumping device 128 within the first pump chamber 118. The first pumping device 128 can be any suitable type of pumping device, and can include, for example, one or more rotors, such as a plurality of intermeshing or cooperating rotors. The one or more rotors can be fixed to respective shafts that extend at least partially through the first pump chamber 118. The shafts, and thus the rotors, can be rotated by any suitable means, such as an electric motor, thereby pumping fluid through the first pump chamber 118.

[0043] The first pump chamber 118 (and the first pumping device 128 therein) is connected between the first fluid inlet 116 and the first fluid outlet 120, such that, in operation, fluid is pumped by the first pumping device 128 into the first fluid inlet 116, from the first fluid inlet 116 to the first fluid outlet 120, and out of the first fluid outlet 120.

[0044] The first vacuum pump 102 also includes a heat exchanger 130. The heat exchanger 130 includes a conduit 132 that passes through at least one of the one or more walls of the first stator 114 (e.g., is embedded therein or formed integrally therewith). In particular, in this embodiment, the conduit 132 is embedded in or formed integrally with the one or more additional walls 126. The conduit 132 can be entirely within the one or more additional walls 126.

[0045] In this embodiment, the conduit 132 includes a conduit inlet 134 and a conduit outlet 136. The conduit inlet 134 is located on the outer surface of the first stator 114. Specifically, in this embodiment, the conduit inlet 134 is located on the outer surface of one or more additional walls 126. The conduit outlet 136 is located on the outer surface of the first stator 114. Specifically, in this embodiment, the conduit outlet 136 is located on the outer surface of one or more additional walls 126.

[0046] The conduit inlet 134 is connected to the purge gas source 106, so that during operation, purge gas from the purge gas source 106 is received at the conduit inlet 134, such as... Figure 1 As indicated by the middle arrow and reference numeral 138. The conduit 132 is configured to deliver the received purge gas through the conduit 132 from the conduit inlet 134 to the conduit outlet 136, as shown. Figure 1 As indicated by the middle arrow and reference numeral 140. The conduit outlet 136 is connected to the second vacuum pump 104, such that during operation, the purge gas exiting the conduit 132 of the heat exchanger 130 via the conduit outlet 136 is delivered to the second vacuum pump 104, as... Figure 1 The middle arrow and reference numeral 142 indicate this.

[0047] In this embodiment, the conduit 132, connecting the conduit inlet 134 and the conduit outlet 136, is separated from the pump chamber 118 by the wall of the first stator 114. In other words, in this embodiment, within the boundary or limit of the first stator 114, the conduit 132 is fluidly isolated or independent from the first pump chamber 118. Therefore, in this embodiment, fluid cannot flow through the wall of the first stator 114 between the conduit 132 and the first pump chamber 118, and vice versa.

[0048] In this embodiment, catheter 132 is a coiled, tortuous, or serpentine catheter. This can... Figure 2 It can be seen more clearly in the middle.

[0049] Further details regarding the heat exchanger 130 and its operation will be referred to below. Figure 2 and Figure 3 To describe in more detail.

[0050] The second vacuum pump 104 can be any suitable type of vacuum pump, such as a dry vacuum pump. The second vacuum pump 104 is configured to pump fluid from the first vacuum pump 102, such as… Figure 1 As indicated by the middle arrow and reference numeral 112 in the attached figure. Therefore, a vacuum or low-pressure environment is created at facility 101. The second vacuum pump 104 is configured to discharge or output the pumped fluid, such as... Figure 1 As indicated by the middle arrow and reference numeral 144. Depending on the application, the pumped fluid can be discharged to any suitable entity. For example, the pumped fluid can be discharged to an emissions reduction system or discharged to the environment.

[0051] The second vacuum pump 104 includes a second housing or stator 146. The second stator 146 includes one or more walls that define a second fluid inlet 148, a second pump chamber 150, and a second fluid outlet 152.

[0052] The second vacuum pump 104 also includes a second pumping device (not shown) located within the second pump chamber. The second pumping device can be any suitable type of pumping device.

[0053] The second vacuum pump 104 also includes a nozzle 154. The nozzle 154 is disposed through one or more walls of the second stator 146. The nozzle 154 is coupled to the conduit outlet 136 such that, in operation, the flow of purge gas is received by the nozzle 154. The nozzle 154 is also structured to deliver the received purge gas into the second pump chamber 150, as Figure 1 indicated by the arrow and reference number 156.

[0054] Figure 2 is a schematic illustration showing an exploded perspective view of the first stator 114 of the first vacuum pump 102 (not to scale).

[0055] In this embodiment, the heat exchanger 130 is located on a first side wall 200 of the first stator 114. The first side wall 200 is disposed between the first wall 122 and the second wall 124.

[0056] In this embodiment, the conduit 132 of the heat exchanger 130 is defined by one or more channels 202 formed on an outer surface of the first side wall 200 and a cover 204 covering the one or more channels 202, thereby defining the conduit 132.

[0057] The one or more channels 202 can be channels or grooves that have been machined or etched into the outer surface of the first side wall 200. The one or more channels 202 can define one or more spiral paths between the conduit inlet 134 and the conduit outlet 136.

[0058] The cover 204 can be a substantially flat sheet or plate. The cover 204 can be formed from the same material as the walls forming the first stator 114 (e.g., the first side wall 200). The material can be a thermally conductive material, such as a metal. The cover 204 can be attached to the first side wall 200 by any suitable attachment means, such as using one or more fasteners. The attachment of the cover 204 to the first side wall 200 is indicated in Figure 2 by the dashed arrow and reference number 206. In some embodiments, a seal or gasket, such as an O-ring, is disposed between the cover 204 and the first side wall 200, thereby reducing or eliminating leakage of the purge gas from the heat exchanger 130.

[0059] In this embodiment, the first stator 114 further comprises two heaters 208. The heaters 208 are disposed or received in respective voids 210 in one or more walls of the first stator 114. Thus, the heaters 208 are at least partially embedded in the first stator 114. In this embodiment, the heaters 208 and the voids 210 in which they are received are elongate. The insertion of the heaters 208 into the voids 210 is indicated in FIG. 2 by dashed arrows and reference numeral 212. Figure 2

[0060] In this embodiment, the voids 210 are formed in the first side wall 200. The voids 210 are positioned proximate to the heat exchanger 130, in particular proximate to the one or more channels 202. More specifically, in this embodiment, the voids 210 are positioned at opposite sides of the one or more channels 202 and adjacent to the channels 202.

[0061] The voids 210 can be defined by respective grooves formed on the outer surface of the first side wall 200 (e.g., by machining) and a cover 204 covering these grooves, thereby defining the voids 210.

[0062] The heaters 208 can be any suitable type of heater, including but not limited to an electric heater. The heaters 208 are configured to heat (i.e., raise) the temperature of at least a portion of one or more walls of the first stator 114. Preferably, the heaters 208 are configured to heat at least a portion of the first side wall 200 forming the conduit 132.

[0063] The heaters 208 can be controlled by a controller (not shown in the figures). In some embodiments, the first stator 114 further comprises one or more temperature sensors, which can be disposed on or embedded in one or more walls of the first stator 114. The one or more temperature sensors can be configured to measure the temperature of the one or more walls of the first stator. The operation of the heaters 208 can be performed based on some function of the temperature measurements obtained by the one or more temperature sensors. For example, in some embodiments, the heaters 208 can be controlled to heat at least a portion of the first side wall 200 (e.g., forming at least a portion of the heat exchanger 130) until the temperature of that portion of the first side wall 200 measured by the one or more temperature sensors reaches a threshold value, at which point the heaters 208 can be controlled to stop or reduce heating. The heaters 208 can be controlled to maintain the temperature of that portion of the first side wall 200 around the threshold value.

[0064] In some embodiments, the distribution of the heaters on the first stator is such that the temperature of the first stator is substantially uniform across the body of the first stator. The heaters can be distributed on the first stator at substantially uniform intervals. The heaters can be controlled by a common controller to achieve the desired uniform temperature of the first stator.

[0065] ​The heaters can be distributed on the first stator in a substantially symmetrical arrangement about the first stator axis. One or more of the heaters can be located in an end cap and / or a top plate of the first stator.

[0066] Figure 3 is a process flow diagram illustrating certain steps of a process 300 performed by the vacuum pumping system 100.

[0067] It should be noted that, Figure 3 Certain process steps depicted in the flow diagrams of Figure 3 and described below can be omitted, or such process steps can be performed in an order other than presented and described below. Moreover, while all of the process steps have been depicted as discrete, time-sequential steps, some of the process steps can actually be performed concurrently or at least overlap to some extent in time.

[0068] At step s302, the first vacuum pump 102 pumps fluid out of the facility 101. The fluid is pumped by the first vacuum pump 102 into the first fluid inlet 116, through the first pump chamber 118, and out of the first fluid outlet 120. The fluid is pumped via the fluid line 110 to the second vacuum pump 104. The first vacuum pump 102 increases the pressure of the pumped fluid entering the second vacuum pump 104.

[0069] In this embodiment, the pumping of fluid by the first vacuum pump 102 tends to cause the temperature of one or more walls of the first stator 114 to increase above ambient temperature. This increase in temperature tends to be caused by the relatively high temperature of the fluid received by the first vacuum pump 102 from the facility 101 and / or friction within the first vacuum pump 102, such as between the fluid and portions of the first vacuum pump 102.

[0070] At step s304, optionally, the controllable heater 208 is controlled to heat or further heat at least a portion of one or more walls of the first stator 114. The controllable heater 208 is controllable to heat at least a portion of one or more walls of the first stator 114 to a predetermined temperature. The controllable heater 208 is controllable to heat at least a portion of the first side wall 200 forming the heat exchanger 130, i.e. a portion of the first side wall that defines the conduit 132 or one or more passages 202.

[0071] At step s306, a purge gas is pumped through the heat exchanger 130. More specifically, the purge gas is pumped from the purge gas source 106 and into the conduit 132 via the conduit inlet 134. The purge gas is then pumped through the conduit 132, from the conduit inlet 134 to the conduit outlet 136. The purge gas is then pumped out of the conduit outlet 136.

[0072] The purge gas can be pumped by any suitable pumping means. For example, in some embodiments, the purge gas source 106 comprises a pump configured to pump the purge gas.

[0073] The purge gas can be any suitable purge gas. Preferably, the purge gas is an inert gas. One example of a purge gas is nitrogen.

[0074] At step s308, the heat exchanger 130 heats the purge gas, i.e. increases the temperature of the purge gas, as the purge gas travels through the conduit 132 of the heat exchanger 130. More specifically, heat is transferred from the relatively hot first side wall 200 at least partially forming the conduit 132 to the relatively cold purge gas flowing through the conduit 132.

[0075] Thus, in this embodiment, the temperature of the purge gas leaving the heat exchanger 130 at the conduit outlet 136 is higher than the temperature of the purge gas entering the heat exchanger 130 at the conduit inlet 134.

[0076] In some embodiments, the heater 208 is controlled to heat the portion of the first stator 114 forming the wall of the heat exchanger 130 such that the temperature of the purge gas leaving the heat exchanger 130 is equal to or exceeds a predetermined threshold temperature. This predetermined threshold temperature can be any suitable temperature, for example, a temperature of between approximately 180 °C and approximately 250 °C, or more preferably a temperature of between approximately 180 °C and approximately 200 °C. This predetermined threshold temperature can be a temperature selected from the group of temperatures consisting of: 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C and 250 °C.

[0077] At step s310, the second vacuum pump 104 pumps the fluid received via the fluid line 110. The fluid is pumped by the second vacuum pump 104 into the second fluid inlet 148, through the second pump chamber 150 and out of the second fluid outlet 152. Depending on the application, the fluid is pumped from the second vacuum pump 104 to any suitable entity.

[0078] At step s312, the heated purge gas is pumped from the heat exchanger 130 to the second vacuum pump 104. The heated purge gas is received at the nozzle 154 of the second vacuum pump 104.

[0079] At step s314, the nozzle delivers or disperses the heated purge gas into the second pump chamber 150 of the second vacuum pump 104. Preferably, the heated purge gas is delivered into the second pump chamber 150 at a high velocity.

[0080] Delivery of the heated purge gas into the second pump chamber 150 advantageously tends to remove solid matter that has deposited on components within the second pump chamber 150. Such solid matter can include byproducts of the process performed by the facility 101 (which can have condensed and settled within the second pump chamber 150), or dust, etc. Advantageously, delivery of the heated purge gas into the second pump chamber 150 tends to prevent solid particles from settling within the second pump chamber 150 and to carry the solid particles out of the second pump chamber 150.

[0081] The relatively high temperature of the purge gas tends to reduce or eliminate a reduction in temperature within the second pump chamber 150 and / or of the walls of the second stator 146 and / or of the pumping means housed therein. This advantageously tends to reduce or eliminate condensation of byproducts present within the pumped fluid. As a result, deposition of solidified byproducts within the second pump chamber 150 tends to be reduced. The temperature within the second pump chamber 150 and / or of the walls of the second stator 146 and / or of the pumping means housed therein can be, for example, a temperature selected from the group of temperatures consisting of: 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, and 250°C.

[0082] Thus, there is provided a process 300 performed by the vacuum pumping system 100.

[0083] Advantageously, the above-described system and method tend to reduce or eliminate accumulation of potentially flammable, corrosive, or otherwise hazardous particulate matter within the second vacuum pump. Furthermore, for example, the impedance of the pumping means (e.g. rotor) of the second vacuum pump tends to be reduced or eliminated. As a result, the pumping efficiency of the second vacuum pump tends to be improved.

[0084] Heating of the first stator by the heater advantageously tends to reduce or eliminate condensation of byproducts present within the pumped fluid within the first pump chamber. As a result, deposition of solidified byproducts within the first pump chamber tends to be reduced. As a result, the pumping efficiency of the first vacuum pump tends to be improved.

[0085] Advantageously, uniform heating of the first stator by the heater tends to be achieved. The net shape of the casting forming the first stator 114 tends to allow for neat placement of the heater to achieve uniform heating.

[0086] Advantageously, the above-described heating of the purge gas can be non-electric, which tends to simplify the power supply on the pump.

[0087] In the above-described embodiments, the first vacuum pump is a mechanical booster pump and can be a Roots type or Roots vacuum pump. However, in other embodiments, the first vacuum pump is a different type of vacuum pump. For example, the first vacuum pump can have any number of stages, pump chambers, rotors, and rotor shafts.

[0088] In the above embodiments, the conduit of the heat exchanger is formed in a side wall of the first stator. However, in other embodiments, the conduit is formed in one or more other walls of the first stator, instead of or in addition to the side wall of the stator. For example, at least a portion of the conduit can be formed in a top wall or a bottom wall of the first stator.

[0089] In the above embodiments, the conduit is a coiled, tortuous or serpentine conduit. However, in other embodiments, the conduit has a different suitable shape. In some embodiments, the conduit includes one or more features that facilitate heat transfer to the purge gas, such as one or more fins that increase the surface area of the conduit wall, and / or one or more flow restrictors that slow the flow of the purge gas through the conduit.

[0090] In the above embodiments, the heat exchanger includes a single conduit. However, in other embodiments, the heat exchanger includes multiple conduits.

[0091] In the above embodiments, the first stator includes a single heat exchanger for heating the purge gas flow. However, in other embodiments, the first stator includes multiple such heat exchangers.

[0092] In the above embodiments, the first stator includes two heaters. However, in other embodiments, the stator includes a different number of heaters, such as only one heater or more than two heaters. In some embodiments, the heaters are omitted.

[0093] In the above embodiments, the heaters are located proximate to the conduit. In particular, the heaters are adjacent to the conduit and on opposite sides of the conduit. However, in other embodiments, one or more of the heaters occupy different locations on the first stator. In some embodiments, the heaters can be distributed (e.g., uniformly) across the first stator so as to provide substantially uniform heating to the walls of the first stator.

[0094] In the above embodiments, the preheated purge gas is delivered from the first vacuum pump to the second vacuum pump, and in particular to the second pump chamber of the second vacuum pump. However, in other embodiments, some or all of the preheated purge gas is delivered to a different location instead of or in addition to the second pump chamber of the second vacuum pump. For example, in some embodiments, heated purge gas can be delivered to one or more respective pump chambers of one or more additional vacuum pumps in addition to the second pump chamber of the second vacuum pump. In some embodiments, heated purge gas is delivered to the first pump chamber of the first vacuum pump. In some embodiments, heated purge gas is not delivered to the second vacuum pump, and the second vacuum pump can be omitted.

[0095] In the above embodiments, the conduit of the heat exchanger is defined by one or more channels and a cover covering the channels. However, in other embodiments, the conduit is formed in a different manner.

[0096] In the above embodiments, the heater is embedded in one or more walls of the first stator. However, in other embodiments, the heater is coupled to one or more stator walls in different ways. For example, the heater can be attached to an outer surface of a wall of the first stator.

[0097] Reference will now be made to Figures 4 to 8 Described are alternative embodiments in which a conduit of a heat exchanger through which a purge gas can flow so as to be heated is provided in a heat transfer device that is removably attached to a vacuum pump stator.

[0098] Figure 4 is a schematic illustration (not to scale) showing a perspective view of an embodiment of a vacuum pump 400.

[0099] In the above embodiments, the vacuum pump 400 can be implemented as the first vacuum pump 102 or the second vacuum pump 104.

[0100] In this embodiment, the vacuum pump 400 comprises a stator 402 comprising a plurality of stator walls 404 that define a pump chamber.

[0101] The vacuum pump 400 further comprises a heat transfer device 406 that is thermally coupled to the stator 402. The heat transfer device 406 is removably attached to an outer surface of one or more stator walls 404 by a plurality of fasteners 408.

[0102] Although Figure 4 A single heat transfer device 406 is shown disposed on a side wall of the stator 402, it will be appreciated that multiple such heat transfer devices can be implemented. One or more of the heat transfer devices can be attached to an outer surface of one or more other walls 404 of the stator 402, including but not limited to a top wall, a bottom wall, and / or a side wall of the stator.

[0103] Figure 5 and 6 is a schematic illustration (not to scale) showing the heat transfer device 406 of this embodiment.

[0104] The heat transfer device 406 comprises a heat conductor 500 and a conduit 502 that passes through the heat conductor.

[0105] The heat conductor 500 is a plate or block of thermally conductive material. The heat conductor 500 can be a heat transfer plate. In this embodiment, the heat conductor 500 is preferably a single piece plate of metal, which is preferably aluminium or an aluminium alloy.

[0106] The conduit 502 is a pipe through which, in use, a purge gas (e.g. nitrogen) passes, thereby heating the purge gas, such as described in more detail above with reference to Figures 1 to 3

[0107] ​The conduit 502 is a coiled, tortuous, or serpentine pipe. The conduit 502 is preferably a single piece of pipe that has been bent into a coil or serpentine.

[0108] The conduit 502 is embedded within the heat conductor 500. In this embodiment, the conduit 502 is cast into the heat conductor 500, thereby embedding the conduit 502 within the heat conductor 500. However, in other embodiments, the conduit 502 can be embedded within the heat conductor 500 in different ways, such as by pressing the conduit 502 onto or into a groove formed in a surface of the heat conductor 500.

[0109] In this embodiment, the conduit 502 is partially embedded within the heat conductor 500. More specifically, a plurality of substantially straight parallel sections 504 of the conduit 502 are embedded within the heat conductor 500, while curved transition sections 506 between the straight parallel sections 504 are spaced apart from (i.e., not embedded within) the heat conductor 500. However, in some embodiments, the conduit 502 can follow a coiled path within the heat conductor 500. Further, in some embodiments, the conduit 502 can be fully embedded within the heat conductor 500.

[0110] Preferably, the conduit 502 is formed of a different material than the material forming the heat conductor 500. The conduit 502 can be formed of, for example, stainless steel or a nickel-based alloy. The heat conductor 500 can be formed of, for example, aluminum, an aluminum alloy, or (e.g., in non-semiconductor applications) copper. Preferably, the heat conductor 500 is formed of a material having a thermal conductivity greater than or equal to 200 W / mK.

[0111] In this embodiment, the conduit 502 includes an inlet 508 and an outlet 510. The inlet 508 is arranged to receive a flow of purge gas from a purge gas supply. The purge gas received at the inlet 508 travels through the conduit 502 and exits the conduit 502 at the outlet 510.

[0112] In this embodiment, the inlet 508 is located at or proximate to a first side 512 of the heat transfer device 406. The outlet 510 is positioned at or proximate to a second side 514 of the heat transfer device 406. The second side 514 is opposite the first side 512.

[0113] In operation, purge gas is supplied from a purge gas source to the inlet 508 of the conduit 502 and caused to flow through the conduit 502. Heat is transferred from the relatively hot stator to the relatively cool purge gas flowing through the conduit 502 via the walls of the heat conductor 500 and the conduit 502. For example, the heat conductor 500 of the heat transfer device 406 attached to the stator of a hot screw pump can be heated to a temperature of approximately 250°C. The heated purge gas exits the conduit 502 via the outlet 510. Thus, the purge gas is provided with a pre-heat before being introduced into a pump chamber of a vacuum pump.

[0114] Advantageously, active electrical heating is often avoided, reducing cost and complexity. Cast-in gas heated pipes are often a low cost passive solution that makes use of reduced installation space, and are often highly reliable.

[0115] Although active heating can be avoided, in some embodiments the heat transfer device can also include one or more heaters. For example, Figure 7 is a schematic illustration (not to scale) showing a heat transfer device 700 including one or more heaters, according to another embodiment.

[0116] The heat transfer device 700 can be thermally coupled to a stator of a vacuum pump (such as the first vacuum pump 102 or the second vacuum pump 104) in the same or similar manner as the heat transfer device 406 shown. Figure 4 For example, the heat transfer device 700 can be removably attached to an outer surface of one or more of the stator walls 404 by a plurality of fasteners.

[0117] The heat transfer device 700 includes a heat conductor 702 and a conduit 704 that passes through the heat conductor 702. The heat conductor 702 can be substantially the same as the heat conductor 500. For example, the heat conductor 702 can be a plate or block of metal, such as aluminum or an aluminum alloy.

[0118] The conduit 704 is a pipe through which, in use, a purge gas (e.g., nitrogen) is passed, thereby heating the purge gas. The conduit 704 can be a stainless steel pipe. In this embodiment, the conduit 704 follows a coiled path within the heat conductor 702. The conduit 704 includes an inlet 712 located at or near a first end 714 of the heat transfer device 700, and an outlet 716 located at or near a second end 718 of the heat transfer device 700, the second end 718 being opposite the first end 714. In operation, purge gas is supplied from a source of purge gas to the inlet 712 of the conduit 704 and caused to flow through the conduit 704. Heat is transferred from the relatively hot stator to the relatively cold purge gas flowing through the conduit 704 via the walls of the heat conductor 702 and the conduit 704. The heated purge gas exits the conduit 704 via the outlet 716. Thus, the purge gas is pre-heated before it is introduced into a pump chamber of a vacuum pump.

[0119] In this embodiment, the heat transfer device 700 also includes a plurality of heaters 708. Although Figure 7A heat transfer device 700 is shown that includes four heaters 708, but those skilled in the art will appreciate that in practice the heat transfer device 700 can include any number of heaters 708, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 heaters. Each heater 708 is received in a respective hole or void 710. In this embodiment, the heaters 708 and the voids 710 in which they are received are elongate. The voids 710 are formed in the thermally conductive body 702.

[0120] The heaters 708 can be any suitable type of heater, including but not limited to electric heaters. The heaters 708 are configured to heat (i.e. raise) the temperature of at least a portion of the thermally conductive body 702.

[0121] The heaters 708 can be controlled by a controller (not shown in the figures). In some embodiments, the heat transfer device 700 further includes one or more temperature sensors, which can be disposed on or embedded in the thermally conductive body 702. The one or more temperature sensors can be configured to measure the temperature of the thermally conductive body 702. The operation of the heaters 708 can be performed based on some function of the temperature measurements made by the one or more temperature sensors. For example, in some embodiments, the heaters 708 can be controlled to heat at least a portion of the thermally conductive body 702 until the temperature of that portion of the thermally conductive body 702 measured by the one or more temperature sensors reaches a threshold value, at which point the heaters 708 can be controlled to stop or reduce heating. The heaters 708 can be controlled to maintain the temperature of that portion of the thermally conductive body 702 around the threshold value.

[0122] In some embodiments, the distribution of the heaters 708 on the thermally conductive body 702 is such that the temperature of the thermally conductive body 702 is substantially uniform. The heaters 708 can be distributed at substantially uniform intervals on the first stator. The heaters can be controlled by a common controller to achieve a desired uniform temperature of the thermally conductive body 702.

[0123] In this embodiment, the heaters 708 are arranged to be spaced apart from one another. The conduit 704 is a coiled conduit that passes through the space between adjacent heaters 708.

[0124] In this embodiment, the heaters 708 and the conduit 704 are arranged within a single common layer or plane within the thermally conductive body 702. Alternatively, the heaters 708 and the conduit 704 can be arranged in different respective layers or planes within the thermally conductive body 702. For example, Figure 8 is a schematic illustration (not drawn to scale) showing a heat transfer device 800 according to yet another embodiment.

[0125] The heat transfer device 800 can be used in the same way as the heat transfer device 700, and can be used in the same way as the heat transfer device 600. Figure 4The heat transfer device 406 is shown thermally coupled to a stator of a vacuum pump (such as the first vacuum pump 102 or the second vacuum pump 104) in the same or similar manner as the heat transfer device 406. For example, the heat transfer device 800 can be removably attached to an outer surface of one or more of the stator walls 404 by a plurality of fasteners.

[0126] The heat transfer device 800 includes a heat conductor 802 and a conduit 804 that passes through the heat conductor 802. The heat conductor 802 can be substantially the same as the heat conductor 500 or the heat conductor 702. For example, the heat conductor 802 can be a plate or a block of metal, such as aluminum or an aluminum alloy.

[0127] The conduit 804 is a pipe through which a purge gas (e.g., nitrogen) passes in use, thereby heating the purge gas. The conduit 804 can be a stainless steel pipe. In this embodiment, the conduit 804 follows a coiled path within the heat conductor 802. The conduit 804 includes an inlet 820 located at or near a first end 822 of the heat transfer device 800, and an outlet 824 located at or near a second end 826 of the heat transfer device 800, the second end 826 being opposite the first end 822. In operation, purge gas is supplied from a source of purge gas to the inlet 820 of the conduit 804 and caused to flow through the conduit 804. Heat is transferred from the relatively hot stator to the relatively cold purge gas flowing through the conduit 804 via the walls of the heat conductor 802 and the conduit 804. The heated purge gas exits the conduit 804 via the outlet 824. Thus, preheating of the purge gas is provided before the purge gas is introduced into a pump chamber of a vacuum pump.

[0128] In this embodiment, the heat transfer device 800 also includes a plurality of heaters 808. Although Figure 8 The heat transfer device 800 is shown including four heaters 808, but one skilled in the art will appreciate that in practice the heat transfer device 800 can include any number of heaters 808, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more than 10 heaters. Each heater 808 is received in a respective hole or void 810. In this embodiment, the heaters 808 and the voids 810 in which they are received are elongate. The voids 810 are formed in the heat conductor 802.

[0129] The heaters 808 can be any suitable type of heater, including but not limited to an electric heater. The heaters 808 can be controlled by a controller, for example using a sensor measurement, as described in more detail above with reference to, for example Figure 7 The heaters 808 can be controlled by a controller, for example using a sensor measurement, as described in more detail above with reference to, for example

[0130] In this embodiment, the heaters 808 and the conduit 804 are arranged in different respective layers or planes within the heat conductor 802. The planes or layers can be substantially parallel to each other.

[0131] In this embodiment, the heat transfer device 800 further comprises a further conduit 812. The further conduit 812 is a pipe through the thermally conductive body 802, and in use, a cooling fluid (e.g. water) passes through the pipe, thereby cooling the thermally conductive body 802. The further conduit 812 is preferably a coiled, tortuous or serpentine conduit. The further conduit 812 can be considered a cooling fluid conduit. The skilled person will appreciate that such a cooling fluid conduit can be implemented in any of the other embodiments of heat transfer devices described herein, such as the heat transfer device 400 described in more detail above with reference to Figure 5 and 6 the heat transfer device 406 described in more detail above with reference to Figure 7 the heat transfer device 700 described in more detail above with reference to

[0132] In this embodiment, the further conduit 812 is arranged in the thermally conductive body 802 in a first layer 814. For example, the further conduit 812 can be provided in a first plane. Furthermore, the plurality of heaters 808 are arranged in the thermally conductive body 802 in a second layer 816. For example, the plurality of heaters 808 can be provided in a second plane. Furthermore, the conduit 804 is arranged in the thermally conductive body 802 in a third layer 818. For example, the conduit 804 can be provided in a third plane. Preferably, the first, second and third layers (or planes) 814, 816, 818 are substantially parallel to each other. In this embodiment, the second layer 816 is provided between the first layer 814 and the third layer 818. That is, the layer of heaters 808 is sandwiched between the layer or plane containing the further conduit 812 and the layer or plane containing the conduit 804. The heat transfer device 800 can be attached to the stator wall such that the third layer 818 is in contact with the stator wall and the first layer 814 is furthest from the stator.

[0133] However, in other embodiments, the order or arrangement of the layers can be different. For example, Figure 9 is a schematic illustration (not to scale) showing a cross-section of a heat transfer device 900 in which the conduit 804, the heaters 808 and the further conduit 812 are arranged in a different way. In this embodiment, the layer or plane 902 containing the conduit 804 is sandwiched between the layer 904 of heaters 808 and the layer or plane 906 containing the further conduit 812. The heat transfer device 900 can be attached to the stator wall such that the layer 904 containing the heaters 808 is in contact with the stator wall and the layer or plane 906 containing the further conduit 812 is furthest from the stator. In this arrangement, heat loss upwards from the heaters 808 tends to be captured by the sweep gas within the conduit 804, and the heaters 808 are also in close proximity to, or in direct contact with, the stator to provide more effective heating thereof. In the event that the heaters 808 are on and the cooling fluid supply to the further conduit 812 is off, the sweep gas tends to provide a protective layer between the heaters 808 and the further conduit 812 to prevent boiling, stress corrosion and calcification of the cooling fluid within the further conduit 812.

[0134] The heat transfer arrangement described above tends to prevent or reduce calcification and stress corrosion. For example, when water is not flowing internally, the purge gas flowing through conduit 804 tends to prevent boiling of the cooling fluid (e.g., water) within the other conduit 812, which tends to be beneficial in preventing calcification and stress corrosion issues of static cooling plates.

[0135] In operation, when cooling of the stator is desired, one or more heaters can be turned off, and flow of the purge gas and the cooling fluid can be turned on. In operation, when heating of the stator and / or the purge gas is desired, flow of the cooling fluid can be turned off, and one or more heaters and flow of the purge gas can be turned on.

[0136] Advantageously, the systems and apparatus described above tend to provide a vacuum pumping system with reduced footprint. For example, the need for additional, separate purge gas heating apparatus can be reduced or eliminated.

[0137] The heat transfer arrangement described above tends to provide relatively low power consumption, and / or to provide a more uniform temperature distribution throughout the pump.

[0138] The systems and apparatus described above tend to provide shorter pump warm-up times by preheating the purge gas. This also saves power in preheating the purge gas in the abatement system if the purge gas is supplied to the abatement system.

[0139] Advantageously, the systems and apparatus described above tend to allow use of larger power heaters. This tends to provide improved preheating of the purge gas and heating of the stator, thereby providing reduced warm-up times of the pump.

[0140] The purge gas flowing through the purge gas conduit tends to be distributed over the stator, thereby reducing the likelihood of hot / cold spots caused by localized heating from the heaters.

[0141] In the above systems and apparatuses, the purge gas conduit can be arranged so that the purge gas flows along the length of the stator between the low vacuum end of the stator and the low vacuum end of the stator. For example, the above heat transfer device can be attached to the stator so that the inlet of the conduit is located at or near one of the high vacuum end or the low vacuum end of the vacuum pump and the outlet of the conduit is located at or near the other of the high vacuum end or the low vacuum end. Under operating conditions, such as high load conditions, where the stages at and near the high vacuum end of the vacuum pump are potentially hotter than the stages at and near the low vacuum end of the vacuum pump, the purge gas can be caused to enter the purge gas conduit at the conduit opening closer to the high vacuum end; the flow of purge gas through the conduit will tend to transfer heat from the high vacuum end to the cooler low vacuum end. Similarly, under operating conditions, such as at extreme conditions, where the stages at and near the low vacuum end of the vacuum pump can be hotter than the stages at and near the high vacuum end of the vacuum pump, the purge gas can enter the purge gas conduit at the conduit opening closer to the low vacuum end; the flow of purge gas through the conduit will tend to transfer heat from the low vacuum end to the cooler high vacuum end. Advantageously, the direction of the purge gas flow through the conduit tends to be variable.

[0142] In the above embodiments, the purge gas conduit can have any suitable dimensions. For example, the purge gas conduit can have an internal diameter of about 5-10 mm, or more preferably about 6 mm. In some embodiments, the purge gas conduit can have an internal diameter of less than or equal to 5 mm, for example 2-4 mm, for example about 3 mm.

[0143] In the above embodiments, the heat conductive body of the heat transfer device can be cast or machined. However, in other embodiments, at least a portion of the heat transfer device, such as the heat conductive body, can be manufactured in a different way, such as using additive manufacturing (AM) techniques. For example, the heat conductive body can be formed using AM to include a network of purge gas conduits therein. Having smaller purge gas conduits in the heat transfer device tends to provide improved protection against calcification and stress corrosion.

[0144] In the above embodiments, the purge gas can be nitrogen. However, in other embodiments, a different purge gas can be used, such as air.

[0145] In the above embodiments, the cooling fluid can be water. However, in other embodiments, a different cooling fluid can be used.

[0146] Reference Signs 100 - vacuum pumping system 100 101 - facility 102 - first vacuum pump 104 - second vacuum pump 106 - purge gas source 108, 112, 144 - fluid flow direction 110 - fluid line 114 - first stator 116 - first fluid inlet 118 - first pump chamber 120 - first fluid outlet 122 - first wall or top wall 124 - second wall or bottom wall 126 - one or more additional walls or side walls 128 - first pumping means 130 - heat exchanger 132 - conduit 134 - conduit inlet 136 - conduit outlet 138, 140, 142, 156 - purge gas flow direction 146 - second stator 148 - second fluid inlet 150 - second pump chamber 152 - second fluid outlet 154 - nozzle 200 - first side wall 202 - one or more channels 204 - lid 206 - direction of movement of lid 208 - heater 210 - void 212 - direction of movement of heater 300 - process s302-s314 - process steps 400 - vacuum pump 402 - stator 404 - stator wall 406 - heat transfer device 408 - fastener 500 - heat conductor 502 - conduit 504 - straight parallel section 506 - curved transition section 508 - inlet 510 - outlet 512 - first side 514 - second side 700 - heat transfer device 702 - heat conductor 704 - conduit 708 - heater 710 - void 712 - inlet 714 - first end 716 - outlet 718 - second end 800 - heat transfer device 802 - thermally conductive body 804 - conduit 808 - heater 810 - void 812 - another conduit 814 - first layer 816 - second layer 818 - third layer 820 - inlet 822 - first end 824 - outlet 826 - second end 900 - heat transfer device 902, 904, 906 - layers

Claims

1. A vacuum pump comprising: a stator comprising one or more stator walls defining a pump chamber; and a heat transfer arrangement coupled to the one or more stator walls, the heat transfer arrangement comprising: a thermally conductive body; and a conduit passing through the thermally conductive body, and in use, purge gas passes through the conduit, thereby heating the purge gas. The heat transfer arrangement is attached to an outer surface of the one or more stator walls.

2. Vacuum pump according to claim 1, wherein, The conduit comprises a pipe embedded within the thermally conductive body.

3. A vacuum pump according to any preceding claim, wherein, The pipe is a stainless steel pipe.

4. The vacuum pump of claim 3, wherein, The thermally conductive body is a plate of thermally conductive material.

5. A vacuum pump according to any preceding claim, wherein, The thermally conductive body comprises aluminium.

6. A vacuum pump according to any preceding claim, wherein, The heat transfer arrangement further comprises one or more heaters embedded therein.

7. A vacuum pump according to any preceding claim, wherein, 8. The vacuum pump of claim 7, wherein: The heat transfer arrangement comprises a plurality of heaters arranged spaced apart from one another; and The conduit is a coiled conduit passing through one or more spaces between heaters. The conduit is a coiled conduit.

9. A vacuum pump according to any preceding claim, wherein, The heat transfer arrangement further comprises:

10. A vacuum pump according to any preceding claim, wherein, a further conduit passing through the thermally conductive body, and in use, a cooling fluid passes through the further conduit, thereby cooling the thermally conductive body. The heat transfer arrangement comprises:

11. A vacuum pump according to any preceding claim, wherein, a further conduit passing through the thermally conductive body arranged to receive a cooling fluid, thereby cooling the thermally conductive body, wherein the further conduit is arranged in the thermally conductive body as a first layer; and a plurality of heaters arranged in the thermally conductive body as a second layer; wherein The conduit is arranged in the thermally conductive body as a third layer; and The third layer is disposed between the first layer and the second layer. The conduit comprises:

12. A vacuum pump according to any preceding claim, wherein, an inlet located at or proximate a first side of the heat transfer arrangement; and an outlet located at or proximate a second side of the heat transfer arrangement, the second side being opposite the first side.

13. The vacuum pump of any preceding claim, wherein: the stator comprises a high vacuum end and a low vacuum end; The conduit comprises: an inlet located at or proximate one of the high vacuum end or low vacuum end; and an outlet located at or proximate the other of the high vacuum end or low vacuum end.

14. A system comprising: a vacuum pump according to any preceding claim; and a source of purge gas configured to supply purge gas into the conduit.

15. A method comprising: providing a vacuum pump according to any of claims 1 to 13; pumping a fluid using the vacuum pump, the fluid being pumped through a pump chamber of the vacuum pump; and flowing purge gas through the conduit of the heat transfer arrangement; wherein when the purge gas flows through the conduit, heat is transferred from the stator to the purge gas via the thermally conductive body, thereby heating the purge gas. ​ ​

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