ICP MASS SPECTROMETER

Abstract

Provided is an ICP mass spectrometer which is able to effectively discharge residual water by limiting the consumption of Ar gas and a fluctuation in supply pressure of an Ar gas source at the time of an Ar gas purge for a coolant system. The ICP mass spectrometer is provided with: a device body part 1; a coolant system 2 that supplies a coolant from a water source 20 to to-be-cooled structure parts including a high-freqency power supply 12, a high-frequency coil 18, and a sample introduction part 13, which need to be cooled; and an Ar gas supply system 3. Intermediate valves V2, V3 are disposed on the downstream side of a main valve V0, a purge gas channel 32 having a purge valve V1, and a meeting point G of the purge gas channel 32. The to-be-cooled structure parts are connected to a cooling-use pipe on the downstream side of the intermediate valves V2, V3. A valve control part 35 in configured to perform intermittent purge control of repeating accumulation and discharge of the Ar gas on the upstream side of the intermediate valves V2, V3 by intermediately opening and closing the intermediate valves V2, V3 where the Ar gas is being sent.

Claims

1. An ICP mass analysis device characterized in that it comprises: a device main body unit which supplies Ar gas for plasma generation and sample gas, via a gas flow rate control unit which controls gas flow rate, to a reaction tube of a plasma torch, ionizes the sample gas by applying a high frequency voltage from a high frequency power supply to a high frequency coil of said plasma torch, and draws in generated sample ions through a sample introduction unit to a mass analyzer to perform mass analysis; a cooling water system in which water cooling piping is connected as a flow passage to cooled structures which require cooling, including said high frequency power supply, said high frequency coil and said sample introduction unit, and which supplies cooling water from a water source to said cooled structures; and an Ar gas supply system in which gas piping is connected as a flow passage to said gas flow rate control unit and which supplies Ar gas from an Ar gas source; wherein, in said cooling water system, there is provided a master valve which is connected as a flow passage on the upstream side of said water cooling piping, a purge gas flow passage which branches from said gas piping and is connected as a flow passage via a purge valve at a location downstream of said master valve so as to merge into said water cooling piping, and an intermediate valve which is connected as a flow passage to said water cooling piping downstream of the merging point of said purge gas flow passage; said cooled structures are connected as a flow passage to said water cooling piping downstream of said intermediate valve; a valve control unit is provided, which performs interlocked opening/closing control of said master valve, said purge valve and said intermediate valve; and said valve control unit, when said master valve is placed into a closed state and said purge valve is placed into an open state and Ar gas is fed via the purge gas flow passage, performs intermittent purge control whereby said intermediate valve is intermittently opened and closed to repeat pressure accumulation and release of Ar gas upstream of said intermediate valve.

2. An ICP mass analysis device as set forth in claim 1, characterized in that, in the purge gas flow passage downstream of said purge valve, there is provided a pipe resistance comprising a pipe of the same diameter as or narrower diameter than the pipe diameter of the purge gas flow passage.

3. An ICP mass analysis device as set forth in claim 1, characterized in that the water cooling piping of said cooling water system branches, downstream of the merging point of said purge gas flow passage, into a bypass flow passage having a first intermediate valve, and a high frequency power supply cooling flow passage to which a second intermediate valve and said high frequency power supply are connected as flow passages in series in that order; said sample introduction unit and said high frequency coil are connected as flow passages downstream of said bypass flow passage and said high frequency power supply cooling flow passage; and said valve control unit, when performing said intermittent purge control, performs control whereby said first intermediate valve and said second intermediate valve are simultaneously placed into an open state, and said bypass flow passage and said high frequency power supply cooling passage are simultaneously purged.

4. An ICP mass analysis device as set forth in claim 1, characterized in that the water cooling piping of said cooling water system branches, downstream of the merging point of said purge gas flow passage, into a bypass flow passage having first intermediate valve, and a high frequency power supply cooling flow passage to which a second intermediate valve and said high frequency power supply are connected as flow passages in series in that order; said sample introduction unit and said high frequency coil are connected as flow passages downstream of said bypass flow passage and said high frequency power supply cooling flow passage; and said valve control unit, when performing said intermittent purge control, performs control whereby said first intermediate valve and said second intermediate valve are alternately placed into an open state one at a time, and said bypass flow passage and said high frequency power supply cooling flow passage are purged one at a time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG. 1 A drawing illustrating the device configuration of an ICP mass analysis device according to the present invention.

[0045] FIG. 2 A drawing illustrating the piping system of the cooling water system and Ar gas supply system in FIG. 1.

[0046] FIG. 3 A drawing illustrating an example of operating flow of the present invention.

[0047] FIG. 4 A drawing illustrating an example of operating flow of the present invention.

[0048] FIG. 5 A drawing illustrating an example of operating flow for reference.

[0049] FIG. 6 A drawing illustrating the device configuration of a conventional ICP mass analysis device

[0050] FIG. 7 A drawing illustrating the piping system of the cooling water system and Ar gas supply system in FIG. 6.

[0051] FIG. 8 A simplified cross-sectional view illustrating the sample introduction unit in an ICP mass analysis device.

[0052] FIG. 9 A drawing illustrating an example of the Ar gas supply system in an ICP mass analysis device.

MODES FOR EMBODYING THE INVENTION

[0053] Embodiments of the present invention will be described below using the drawings.

[0054] FIG. 1 is a drawing illustrating the device configuration of an ICP mass analysis device A according to the present invention, and FIG. 2 is a drawing illustrating the piping system of the cooling water system and Ar gas supply system 3 in the ICP mass analysis device A of FIG. 1. For constituent parts which are the same as in the conventional ICP mass analysis device 100 described in FIGS. 6 and 7, the same reference symbols will be assigned and a portion of the description will be thus omitted.

[0055] In the ICP mass analysis device A according to the present invention, the device main body control unit 16 composed of a computer device as in the conventional ICP mass analysis device 100, is provided with a valve control unit 35 which performs execution of a valve control program which implements Ar gas purging based on opening and closing of a master valve V0, purge valve V1, first intermediate valve V2 and second intermediate valve V3.

[0056] This valve control unit 35, when draining of the cooling water system 2 is to be performed, as a maintenance mode, performs intermittent purge control in which the master valve V0, purge valve V1, first intermediate valve V2 and second intermediate valve V3 are operated according to an operation flow as described below. Namely, when master valve V0 is placed into a closed state and purge valve V1 is placed into an open state and Ar gas is fed into the cooling water system 2 via the purge gas flow passage 32, the first intermediate valve V2 and second intermediate valve V3 are maintained in a closed state until the time necessary for pressure accumulation (pressure accumulation time T) has elapsed and are then placed into an open state, after which they are again placed into a closed state, which is maintained until pressure accumulation time T has elapsed, after which the valves are placed into an open state. The operation of opening and closing intermittently in this manner is repeated to perform control for repeating the pressure accumulation and release of Ar gas.

[0057] Furthermore, in the present embodiment, a pipe resistance 36 which restricts inflow of gas is provided in the purge gas flow passage 32 downstream of the purge valve V1. The pipe resistance 36 is selected to have a magnitude of resistance sufficient to prevent sudden pressure fluctuation upstream of the purge valve V1 when the purge valve V1 is opened.

[0058] Specifically, in the middle of the purge gas flow passage 32 formed from gas pipe with an inside diameter of 4 mm, a pipe with a narrower inside diameter of 0.5 mm is connected as a (coiled) pipe resistance 36 with a length of 1 m, thereby increasing the pipe resistance of the purge gas flow passage 32.

[0059] Connecting the pipe resistance 36 causes the gas flow rate downstream of the pipe resistance 36 to decrease, so the time required for pressure accumulation in the intermittent purge control described above (pressure accumulation time T), i.e. the waiting time until the accumulated Ar gas pressure becomes about the same as the pressure upstream of the purge valve V1, is preset in accordance with the magnitude of the pipe resistance 36 on the basis of preliminary experiments. Furthermore, the time during which the intermediate valves V2, V3 are opened (opening time F) is also set in advance. The description here will assume that the pressure accumulation time T has been set at 10 seconds and the opening time F has been set at 5 seconds.

[0060] Furthermore, the purge count n (used as the argument n in the operation flow described later) is also set in advance. In the following embodiment example, it will be assumed that this was set so as to perform five purges (n=5).

[0061] Next, the gas purge operation flow under the aforesaid conditions will be described.

(Operation Flow-1)

[0062] FIG. 3 is a flow chart explaining an example of the gas purging operation flow using the valve control unit 35 of the ICP mass analysis device A.

[0063] When an input operation is performed to start maintenance mode with the input device of the device main body control unit 16 in order to perform draining of the cooling water system 2, the parameter n which counts the number of purges is set to the initial value 0, the master valve V0 closes, and the first intermediate valve V2 and second intermediate valve V3 are closed nearly simultaneously. It will be noted that the purge valve V1 is closed to begin with (ST101).

[0064] Next, the purge valve V1 is opened and the open state is maintained until a preset pressure accumulation time T (10 seconds) elapses. As a result, the Ar gas of the purge gas flow passage 32 is accumulated until its pressure reaches the same level as the pressure upstream of the purge valve V1 (ST102). The first time, since cooling water remains downstream of the check valve GV, by way of exception, Ar gas is accumulated in the pipe only up to the check valve GV, but in the second and subsequent pressure accumulation described below, pressure accumulation occurs also downstream of the check valve GV.

[0065] Next, the first intermediate valve V2 and second intermediate valve V3 are opened for a preset opening time F (5 seconds) to perform purging. During this time, the purge valve V1 is maintained in an open state, and Ar gas which has accumulated in the purge gas flow passage 32 is released and flows downstream, draining the residual water in the downstream direction.

[0066] At this time, 1 is added to the purge count parameter n (ST103).

[0067] Next, the current purge count is checked on the basis of the parameter n (ST104). If the purge count parameter n is less than 5, the processing of ST102 through ST104 is repeated.

[0068] Once parameter n becomes 5, control proceeds to ST105.

[0069] After confirming that the set number (n=5) of purges has been carried out in ST104, the master valve V0 and purge valve V1 are closed (ST105). Purging is thereby ended.

[0070] The first intermediate valve V2 and second intermediate valve V3 are then also closed (ST106). Device operation is thereby completed.

[0071] According to the above procedure, draining can be efficiently carried out through gas purging while reducing the consumption of Ar gas.

(Operation Flow-2)

[0072] FIG. 4 is a flow chart explaining another example of the gas purge operation flow using the valve control unit 35 of the ICP mass analysis device A. The difference from operation flow-1 described above is that the first intermediate valve V2 and second intermediate valve V3 are alternately opened and closed in order to carefully purge flow passage (bypass flow passage) 23 and flow passage (high frequency power supply cooling flow passage) 24 one by one. The operation in this case is as follows.

[0073] When an input operation to start maintenance mode is performed using the input device of the device main body control unit 16, the parameter n which counts the number of purges is set to the initial value 0, the master valve V0 closes, and the first intermediate valve V2 and second intermediate valve V3 are closed nearly simultaneously. It will be noted that the purge valve V1 is closed to begin with (ST201).

[0074] Next, the purge valve V1 is opened and the open state is maintained until a preset pressure accumulation time T (10 seconds) elapses. As a result, the Ar gas of the purge gas flow passage 32 is accumulated until its pressure reaches the same level as the pressure upstream of the purge valve V1 (ST202). The first time, since cooling water remains downstream of the check valve GV, by way of exception, Ar gas is accumulated in the pipe only up to the check valve GV, but in the second and subsequent pressure accumulation described below, pressure accumulation occurs also downstream of the check valve GV.

[0075] Next, the first intermediate valve V2 is opened for a preset opening time F (5 seconds) to perform purging. During this time, the purge valve V1 is maintained in an open state, while the master valve V0 and second intermediate valve V3 are maintained in a closed state. As a result, the Ar gas which has accumulated in the purge gas flow passage 32 is released and flows downstream, draining the residual water in the downstream direction. At this time, 1 is added to the purge count parameter n (ST203).

[0076] Next, with the purge valve V1 remaining open, the first intermediate valve V2 is closed, and the open state is maintained until a preset pressure accumulation time T (10 seconds) elapses. As a result, the Ar gas of the purge gas flow passage 32 is accumulated until its pressure reaches the same level as the pressure upstream of the purge valve V1 (ST204).

[0077] Next, the second intermediate valve V3 is opened for a preset opening time F (5 seconds) and purging is performed. During this time, the purge valve V1 is maintained in an open state, while the master valve V0 and first intermediate valve V2 are maintained in a closed state. As a result, the Ar gas which has accumulated in the purge gas flow passage 32 is released and flows downstream, draining the residual water in the downstream direction. The purge count parameter n remains unchanged at this time (ST205).

[0078] Next, the current purge count is checked on the basis of the parameter n (ST206). If the purge count parameter n is less than 5, the processing of ST202 through ST205 is repeated.

[0079] Once parameter n becomes 5, control proceeds to ST207.

[0080] After confirming that the set number (n=5) of purges has been carried out in ST206, the master valve V0 and purge valve V1 are closed (ST207). Purging is thereby ended.

[0081] The first intermediate valve V2 and second intermediate valve V3 are then also closed (ST208). Device operation is thereby completed.

[0082] According to the above procedure, draining can be efficiently carried out through gas purging while reducing the consumption of Ar gas.

(Reference Operation Flow)

[0083] Two operation flows constituting embodiments of the present invention were described above. The above-described operation flows-1 and 2 make it possible to achieve a reduction in Ar gas consumption and a reduction in supply pressure fluctuation of the Ar gas supply system, which are the two object of the present invention.

[0084] By contrast, when the object is only the latterreduction in supply gas fluctuation, if the flow resistance of cooling water flowing through the water cooling piping is low and draining is possible with the pressure of the purge gas which has passed through the pipe resistance 36, the device configuration can be simplified.

[0085] Namely, it is possible to reduce supply pressure fluctuation simply by using the pipe resistance 36 of the purge gas flow passage 32, without performing intermittent purge control. The reference operation flow for this case is shown in FIG. 5.

[0086] When an input operation is performed to start maintenance mode with the input device of the device main body control unit 16, the master valve V0 closes, and the first intermediate valve V2 and the second intermediate valve V3 are closed nearly simultaneously. It will be noted that the purge valve V1 is closed to begin with (ST301).

[0087] Next, the purge valve V1, first intermediate valve V2 and second intermediate valve V3 are opened simultaneously, and the open state is maintained until a preset opening time F (for example, 30 seconds) elapses (ST302). The master valve V0 is maintained in a closed state. At this time, Ar gas flows in continuously, but the inflow of gas is restricted due to the existence of the pipe resistance 36, so the supply pressure does not drop significantly, making it possible to prevent adverse effects due to pressure fluctuation upstream of the purge valve V1.

[0088] Next, after the opening time has elapsed, the master valve V0, purge valve V1, first intermediate valve V2 and second intermediate valve V3 all close, whereby operation of the device is completed (ST303).

[0089] Embodiments of the present invention have been described above, but the present invention is not limited to these embodiments and of course includes various other configurations that do not depart from the gist of the present invention.

[0090] For example, in the embodiments described above, a structure involving switching the first intermediate valve V2 of flow passage (bypass flow passage) 23 and the second intermediate valve V3 of flow passage (high frequency power supply cooling flow passage) 24 was employed, but the invention can also be applied with a cooling water system of a simpler structure in which no bypass flow passage is provided and only a single intermediate valve is arranged in a single flow passage.

[0091] Furthermore, in the embodiments described above, a pipe resistance 36 was provided in the purge gas flow passage 32 to reduce pressure fluctuation on the upstream side, but if instead no pipe resistance 36 is provided and only intermittent purge control is performed using the valve control unit 35, intermittent pressure fluctuation of upstream supply pressure will occur, but this is still effective because the magnitude of supply pressure fluctuation can be reduced as compared to the free-flowing state of the prior art.

FIELD OF INDUSTRIAL APPLICATION

[0092] The present invention can be employed for ICP mass analysis devices.

DESCRIPTION OF REFERENCE SYMBOLS

[0093] A ICP mass analysis device [0094] 1 Device main body unit [0095] 2 Cooling water system [0096] 3 Ar gas supply system [0097] 11 Plasma torch [0098] 12 High frequency power supply [0099] 13 Sample introduction unit [0100] 14 Mass analysis unit (mass analyzer) [0101] 15 Gas flow rate control unit [0102] 16 Device main body control unit [0103] 18 High frequency coil [0104] 19 Nebulizer [0105] 20 Chiller (water source) [0106] 23 Bypass flow passage [0107] 24 High frequency power supply cooling flow passage [0108] 26 Sample introduction unit cooling flow passage [0109] 27 High frequency coil cooling flow passage [0110] 32 Purge gas flow passage