Nitrogen supply system and method for supplying nitrogen by using same

Abstract

The invention relates to a nitrogen supply system which comprises a nitrogen supply source, a plurality of supply main pipelines in fluid communication with the nitrogen supply source and overflow valves arranged in the supply main pipelines, each supply main pipeline is communicated to a corresponding nitrogen user group located in a closed plant, and the nitrogen user group comprises a plurality of nitrogen users; the excess flow valve is located outside the plant, and when the flow of nitrogen flowing through the excess flow valve does not exceed a preset flow threshold value, the excess flow valve is kept in an open state so that the nitrogen can be supplied to all nitrogen users; and when the flow of the nitrogen flowing through the excess flow valve exceeds a preset flow threshold value, the excess flow valve is automatically switched to a closed state. The invention also relates to a method for supplying nitrogen by using the system. According to the nitrogen supply system disclosed by the invention, the overflow valves are arranged outside the closed factory building in each supply main pipeline, so that the nitrogen can be prevented from excessively leaking into the factory building when a leakage area exists at a nitrogen user.

Description

Technical Field

[0001] The present invention relates to the technical field of nitrogen supply, and in particular to a nitrogen supply system and a method for supplying nitrogen using the nitrogen supply system. Background Art

[0002] There are usually many nitrogen users in a closed plant (for example, in an extrusion building, including a large bag unpacking and unloading station with nitrogen demand, an additive daytime warehouse, a filter receiver, and an extruder user, etc.), which use nitrogen very frequently and have a very large peak gas volume. However, in such a closed plant, if there is a leak at one or more of the nitrogen users, a large amount of nitrogen will be leaked into the atmosphere of the plant and accumulated in the plant, which may cause the operators in the plant to suffocate due to the accumulation of leaked nitrogen.

[0003] Various types of nitrogen supply systems are known in the prior art. These nitrogen supply systems may have supply pipelines for supplying nitrogen, and generally multiple supply pipelines are provided in consideration of safety efficiency and safety redundancy. However, these nitrogen supply systems all ignore the risk of suffocation caused by excessive leakage of nitrogen in a closed plant, and do not provide an effective solution to this possible risk. Summary of the invention

[0004] The present invention is proposed based on such background, and aims to provide an improved nitrogen supply system to overcome the above and / or other problems existing in the prior art.

[0005] According to one aspect of the present invention, there is provided a nitrogen supply system, comprising a nitrogen supply source, a plurality of main supply lines fluidly connected to the nitrogen supply source, and an excess flow valve arranged in each of the main supply lines, each of the main supply lines being connected to a corresponding nitrogen user group located in a closed factory building, the nitrogen user group comprising a plurality of nitrogen users; wherein the excess flow valve is located outside the closed factory building, and the excess flow valve is configured such that: when the flow rate of nitrogen flowing through the excess flow valve does not exceed a predetermined flow rate threshold of the excess flow valve, the excess flow valve remains in an open state so that nitrogen can be supplied to each nitrogen user along each main supply line; and when the flow rate of nitrogen flowing through the excess flow valve exceeds the predetermined flow rate threshold, the excess flow valve automatically switches to a closed state.

[0006] As an implementation manner, the predetermined flow rate threshold is selected to be equal to the maximum nitrogen consumption flow rate of all nitrogen users in the nitrogen user group connected to the corresponding main supply line within the same period.

[0007] As an implementation manner, the predetermined flow rate threshold is selected to be greater than the maximum nitrogen consumption flow rate of all nitrogen users in the nitrogen user group connected to the corresponding main supply line during the same period.

[0008] As an implementation manner, the predetermined flow rate threshold is selected to be equal to 1.1-1.3 times the maximum nitrogen consumption flow rate in the same period.

[0009] As an embodiment, the excess flow valve includes a valve housing and a valve body and a spring assembly arranged in the valve housing; wherein the valve housing is provided with an inlet intended to be fluidically connected to the nitrogen supply source, an outlet intended to be fluidically connected to a downstream nitrogen user group, and a valve seat arranged in the valve housing near the outlet; the valve body includes a valve stem and a valve disc; the spring assembly includes a spring arranged around the valve stem; wherein the excess flow valve is capable of remaining open when the pressure between the inlet side and the outlet side is balanced, and when there is an abnormal pressure drop between the inlet side and the outlet side that is greater than a predetermined value, the valve body of the excess flow valve is driven by the spring assembly so that the valve disc of the valve body abuts against the valve seat to close the outlet, and the predetermined value is associated with the predetermined flow threshold of the excess flow valve.

[0010] As an embodiment, a pressure balancing port is provided on the valve disc, and the pressure balancing port can balance the pressure on the inlet side and the outlet side of the excess flow valve when the flow rate of nitrogen flowing through the excess flow valve is restored to not more than a predetermined flow threshold, thereby returning the excess flow valve to an open state.

[0011] As an embodiment, the abnormal pressure drop indicates that there are one or more leakage points at the nitrogen user group located in the closed factory building or at the section of the main supply line located in the closed factory building.

[0012] According to another aspect of the present invention, a method for supplying nitrogen using the nitrogen supply system as described above is provided, the method comprising the following steps:

[0013] Supplying nitrogen from a nitrogen supply source through a corresponding supply main line through an open flow valve to a nitrogen user group located in a closed plant building;

[0014] In the case where the flow rate of nitrogen flowing through the excess flow valve does not exceed a predetermined flow rate threshold, the excess flow valve is continuously kept in an open state so that nitrogen can be supplied to various nitrogen users along various supply main lines; and

[0015] When the flow rate of nitrogen flowing through the excess flow valve exceeds a predetermined flow rate threshold, the excess flow valve automatically switches from an open state to a closed state to cut off the supply of nitrogen from the nitrogen supply source to each nitrogen user.

[0016] As an implementation manner, when the flow rate of nitrogen flowing through the excess flow valve is restored to not exceed the predetermined flow rate threshold, the excess flow valve automatically restores from a closed state to an open state.

[0017] As an implementation manner, the predetermined flow rate threshold is selected to be equal to or greater than the maximum nitrogen consumption flow rate of all nitrogen users in the nitrogen user group connected to the corresponding main supply line during the same period.

[0018] By adopting the nitrogen supply system according to the present invention, in a relatively closed factory building (such as an extrusion building), an excess flow valve for preventing excessive nitrogen is installed on the main supply line of nitrogen supply, especially outside the closed factory building, so that when the nitrogen flow rate flowing through the excess flow valve exceeds a predetermined flow rate threshold, the excess flow valve can be actively cut off and kept closed, thereby preventing a large amount of nitrogen from leaking into the closed factory building to cause a risk of suffocation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other features and advantages of the present invention will become more readily understood through the following description with reference to the accompanying drawings, in which:

[0020] Figure 1 is a schematic diagram of a nitrogen supply system according to an embodiment of the present invention;

[0021] Figure 2 To set in Figure 1 A cross-sectional view of an excess flow valve in a nitrogen supply system in FIG. 1 ; and

[0022] Figure 3 The present invention is a flow chart of a method for supplying nitrogen using a nitrogen supply system according to an embodiment of the present invention.

[0023] All the drawings are only schematic and not necessarily drawn to scale, and they only show those parts necessary for explaining the present invention, and other parts are omitted or only mentioned. That is, in addition to the parts shown in the drawings, the present invention may also include other parts. DETAILED DESCRIPTION

[0024] Embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, many specific details are set forth so that those skilled in the art can more fully understand and implement the present invention. However, it is obvious to those skilled in the art that the present invention may be implemented without some of these specific details. In addition, it should be understood that the present invention is not limited to the specific embodiments described. On the contrary, it is contemplated that the present invention may be implemented with any combination of the features and elements described below, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments and advantages are for illustrative purposes only and should not be regarded as elements or limitations of the claims unless explicitly stated in the claims. The terms "including" and "having" are used to express an open-ended inclusion meaning and mean that additional elements / components may exist in addition to the listed elements / components.

[0025] As mentioned in the background art, in a closed plant, if there is a leak at one or more nitrogen users (for example, there is a leak in the structure of the nitrogen user itself or there is a leak in the supply pipeline for the nitrogen user), a large amount of nitrogen will leak into the atmosphere, causing the operators in the closed plant to suffocate due to the accumulation of leaked nitrogen. In response to this possible safety risk, the applicant has proposed an improved nitrogen supply system that can effectively solve this safety hazard.

[0026] Figure 1 Schematic diagram of a nitrogen supply system according to an embodiment of the present invention. The nitrogen supply system 1 according to the present invention comprises a nitrogen supply source 2 and a plurality of (eg, Figure 1 There are four supply main lines 3 (shown in the figure), each of which is connected to a nitrogen user group 4 including multiple nitrogen users located in a closed plant 6. For example, each supply main line 3 may be connected to multiple supply sub-lines (not specifically shown in the figure), and these supply sub-lines are connected to the multiple nitrogen users one by one, thereby realizing fluid connection between each supply main line 3 and the multiple nitrogen users.

[0027] In order to avoid the suffocation hazard caused by the leakage of nitrogen in the closed plant 6, an overflow valve 5 is provided on each supply main line 3 upstream of the nitrogen user group 4. Figure 1As shown, the excess flow valve 5 is located outside the closed plant. This setting is very advantageous because it can effectively avoid the presence of a leakage point in the plant area downstream of the excess flow valve, and the excess flow valve can be closed in time to avoid the risk of nitrogen asphyxiation to the employees in the plant. When the flow rate of nitrogen flowing through the excess flow valve 5 in the supply main line 3 does not exceed the predetermined flow threshold, the excess flow valve 5 remains in an open state so that nitrogen can be supplied to each nitrogen user along each supply main line 3. However, when the flow rate of nitrogen flowing through the excess flow valve 5 in the supply main line 3 exceeds the predetermined flow threshold, the excess flow valve 5 automatically switches to a closed state. For example, when the flow rate upstream of the excess flow valve 5 increases abnormally, the pressure drop between the inlet side and the outlet side of the excess flow valve 5 also increases abnormally, which may indicate that there is a leakage point at the nitrogen user group or the section of the supply main line 3 located in the closed plant 6. By setting such an excess flow valve, it is possible to avoid excessive leakage of nitrogen into the plant 6 when there is a leakage area or a damage point at the nitrogen user group.

[0028] In actual application scenarios, for example, in a nitrogen supply system 1 for a closed extrusion building, four supply main lines 3 can be set, which correspond to four different user groups SCD031-SCD034 (see Figure 1 ), each user group includes multiple different sub-users. In addition, a total of four excess flow valves 5 are installed outside the extrusion building to ensure that all nitrogen users in the extrusion building are connected downstream of these excess flow valves. Next, the setting of the predetermined flow threshold of each excess flow valve will be described in detail according to the nitrogen usage of different user groups.

[0029] SCD031 user group: Among the sub-users included in this user group (for example, all additive daytime bins and filter receivers, additive loss-in-weight scale filters, extruder feed hoppers and extruder screw seals, etc.), half of the * part in Table 1 is not included in the flow calculation (for example, considering that only half of the sub-users involved (such as filter receivers) will be backflushed), and the remaining users are included in the calculation. Finally, the calculated total amount is the predetermined flow threshold of the over-flow valve corresponding to this user group.

[0030] In other words, the maximum nitrogen consumption flow rate that may occur simultaneously among the sub-users in the user group is the tripping threshold of the excess flow valve corresponding to the user group.

[0031] Table 1

[0032]

[0033]

[0034] SCD032 user group: Among the sub-users included in this user group (for example, all extruder large screw conveyors, peroxide unloading tanks, additive unloading stations, etc.), a part of Table 2 uses continuous nitrogen flow (for example, the part without * mark), which should all be included in the flow calculation; while another part of Table 2 (for example, the part marked with *) uses discontinuous nitrogen flow. For example, there are up to three sub-users (such as unloading stations) working at the same time, so only the three sub-users with discontinuous flow are included in the calculation. Finally, the calculated total amount is the predetermined flow threshold of the excess flow valve corresponding to this user group. Similarly, the maximum nitrogen consumption flow that may occur simultaneously among the sub-users in this user group is the tripping threshold of the excess flow valve corresponding to this user group.

[0035] Table 2

[0036]

[0037] SCD033 user group: Among the sub-users included in this user group (for example, all additive system rotary valves), only three sub-users (such as rotary valves) are running at the same time, so only the required flow of three sub-users in Table 3 needs to be included in the calculation, and the multiplication factor of 1.1 can be considered on the basis of the total amount. In other words, the maximum nitrogen consumption flow that may occur simultaneously by the sub-users in this user group multiplied by an appropriate multiplication factor is the tripping threshold of the excess flow valve corresponding to this user group.

[0038] Table 3

[0039]

[0040] SCD034 user group: All sub-users included in this user group use continuous nitrogen flow. Therefore, when considering the setting of the predetermined flow threshold of the overflow valve, all users in Table 4 need to be included in the calculation, and the multiplication factor of 1.3 can be considered on the basis of the total amount. Similarly, the maximum nitrogen consumption flow rate that may occur simultaneously among the sub-users in this user group multiplied by an appropriate multiplication factor is the tripping threshold of the overflow valve corresponding to this user group.

[0041] Table 4

[0042]

[0043]

[0044] As can be seen from the above, the predetermined flow threshold of the excess flow valve 5 set on each supply main line 3 is selected to be equal to (for example, corresponding to SCD031-SCD032) or slightly greater than (for example, corresponding to SCD033, which has a multiplication factor of 1.1, and corresponding to SCD034, which has a multiplication factor of 1.3, or other suitable multiplication factors can also be selected, such as between 1.1-1.3) the maximum nitrogen consumption flow of all nitrogen users connected to the corresponding supply main line 3 in the same period. In this way, by setting such an excess flow valve 5 and setting the predetermined flow threshold of the excess flow valve 5 in the above manner, it is possible to determine whether there is a leakage point in the nitrogen user according to the open and closed state of the excess flow valve 5, and avoid the safety risks caused by nitrogen leakage by blocking the excess flow valve.

[0045] Next, we will combine Figure 2 The specific structure of the excess flow valve 5 discussed above is explained.

[0046] like Figure 2 As shown, the excess flow valve 5 comprises a valve housing 51, a valve body 52 and a spring assembly 53 arranged in the valve housing 51. The valve housing 51 is provided with an inlet 511 intended to be communicated with the nitrogen supply source 2, an outlet 512 intended to be communicated with the downstream nitrogen user group 4, and a valve seat 513 arranged in the valve housing 51 near the outlet 512, which is formed as an annular seat portion in the valve housing 51. The valve body 52 comprises a valve stem 521 and a valve disc 522, which are particularly formed in one piece. A guide sleeve 54 is also connected to the valve housing 51, and the valve stem 521 of the valve body 52 passes through the guide sleeve 54 so as to be able to slide relative to the guide sleeve 54, and the guide sleeve 54 can provide a guiding effect for the movement of the valve stem 521. A first spring seat 532 is provided on the side of the valve stem 521 close to the guide sleeve 54, and a second spring seat 533 is provided at the free end close to the valve stem 521. The spring assembly 53 includes a spring 531 arranged around the valve stem 521 and constrained between a first spring seat 532 and a second spring seat 533. In order to limit any undesired axial movement of the guide sleeve 54 and the second spring seat 533, a first locking nut 55 and a second locking nut 56 are provided respectively.

[0047] During operation of the nitrogen supply system 1, the valve body 52 can remain open when the pressure between the inlet side and the outlet side is balanced, and when there is an abnormal pressure drop greater than a predetermined value between the inlet side and the outlet side, the valve body 52 will be urged by the spring assembly 53 to make the valve disc 522 of the valve body 52 abut against the valve seat 513 to close the outlet 512. Since the change in pressure drop is directly related to the change in the flow rate or flow velocity of nitrogen passing through the excess flow valve 5, the predetermined value for determining whether there is an abnormal pressure drop is associated with the predetermined flow threshold of the excess flow valve mentioned above.

[0048] Still see Figure 2 A pressure balancing port 5221 is also provided on the valve disc 522. The pressure balancing port 5221 can balance the pressures on the inlet and outlet sides of the excess flow valve when the flow rate of nitrogen flowing through the excess flow valve is restored to not more than a predetermined flow threshold, thereby returning the excess flow valve to an open state to resume supplying nitrogen to various downstream nitrogen users.

[0049] Next, see Figure 3 A method for supplying nitrogen using the nitrogen supply system according to the present invention is described. In this method, the following steps may be mainly included:

[0050] Supplying nitrogen from a nitrogen supply source through a corresponding supply main line through an open flow valve to a nitrogen user group located in a closed plant building;

[0051] In the case where the flow rate of nitrogen flowing through the excess flow valve does not exceed a predetermined flow rate threshold, the excess flow valve is continuously kept in an open state so that nitrogen can be supplied to various nitrogen users along various supply main lines; and

[0052] When the flow rate of nitrogen flowing through the excess flow valve exceeds a predetermined flow rate threshold, the excess flow valve automatically switches from an open state to a closed state to cut off the supply of nitrogen from the nitrogen supply source to each nitrogen user.

[0053] Advantageously, when the flow rate of nitrogen flowing through the excess flow valve is restored to not more than a predetermined flow rate threshold, the excess flow valve automatically returns from a closed state to an open state.

[0054] In this way, by installing an excess flow valve to prevent excessive nitrogen on the main supply line of nitrogen, the excess flow valve can be actively cut off and kept closed when the nitrogen flow passing through the excess flow valve exceeds a predetermined flow threshold, thereby preventing a large amount of nitrogen from leaking into a closed factory building and causing a risk of suffocation. After the leakage risk is eliminated, the excess flow valve can still be reopened to restore the normal supply of nitrogen.

[0055] It should be noted that the embodiments described above are only to be considered as exemplary, and the present invention is not limited to these embodiments. By considering the contents of this specification, those skilled in the art can make various changes and modifications without departing from the scope or spirit of the present invention. The true scope of the present invention is limited by the appended claims and equivalents.

Claims

1. A nitrogen supply system, the nitrogen supply system (1) comprising a nitrogen supply source (2), a plurality of supply main pipes (3) in fluid communication with the nitrogen supply source, and an excess flow valve (5) arranged in each of the supply main pipes, each of the supply main pipes being connected to a corresponding nitrogen user group (4) located in a closed plant (6), the nitrogen user group comprising a plurality of nitrogen users; in, The excess flow valve is located outside the closed plant (6), and the excess flow valve is configured such that: when the flow rate of nitrogen flowing through the excess flow valve (5) does not exceed a predetermined flow rate threshold of the excess flow valve, the excess flow valve remains in an open state so that nitrogen can be supplied to various nitrogen users along various supply main lines (3); and when the flow rate of nitrogen flowing through the excess flow valve (5) exceeds the predetermined flow rate threshold, the excess flow valve (5) automatically switches to a closed state.

2. The nitrogen supply system according to claim 1, wherein: The predetermined flow rate threshold is selected to be equal to the maximum nitrogen consumption flow rate of all nitrogen users in the nitrogen user group (4) connected to the corresponding supply main line (3) within the same period.

3. The nitrogen supply system according to claim 1, wherein: The predetermined flow rate threshold is selected to be greater than the maximum nitrogen consumption flow rate of all nitrogen users in the nitrogen user group (4) connected to the corresponding supply main line (3) during the same period.

4. The nitrogen supply system according to claim 3, wherein: The predetermined flow rate threshold is selected to be equal to 1.1-1.3 times the maximum nitrogen consumption flow rate in the same period.

5. The nitrogen supply system according to any one of claims 1 to 4, wherein: The excess flow valve (5) comprises a valve housing (51), a valve body (52) and a spring assembly (53) arranged in the valve housing (51); wherein the valve housing (51) is provided with an inlet (511) intended to be in fluid communication with the nitrogen supply source, an outlet (512) intended to be in fluid communication with a downstream nitrogen user group, and a valve seat (513) arranged in the valve housing (51) near the outlet (512); the valve body (52) comprises a valve stem (521) and a valve disc (522); the spring assembly (53) comprises a spring (531) arranged around the valve stem (521); The excess flow valve (5) is capable of remaining open when the pressure between the inlet side and the outlet side is balanced, and when there is an abnormal pressure drop between the inlet side and the outlet side that is greater than a predetermined value, the valve body (52) of the excess flow valve is driven by the spring assembly (53) so that the valve disc (522) of the valve body abuts against the valve seat (513) to close the outlet, and the predetermined value is associated with the predetermined flow threshold of the excess flow valve.

6. The nitrogen supply system according to claim 5, wherein: The valve disc (522) is provided with a pressure balancing port (5221), which can balance the pressures on the inlet and outlet sides of the excess flow valve when the flow rate of nitrogen flowing through the excess flow valve is restored to a value not exceeding a predetermined flow rate threshold, thereby returning the excess flow valve to an open state.

7. The nitrogen supply system according to claim 5, wherein: The abnormal pressure drop indicates that one or more leakage points exist at the nitrogen user group located in the closed plant or at the section of the main supply line located in the closed plant.

8. A method for supplying nitrogen using the nitrogen supply system according to any one of claims 1 to 7, the method comprising the following steps: Supplying nitrogen from a nitrogen supply source through a corresponding supply main line through an open flow valve to a nitrogen user group located in a closed plant building; In the case where the flow rate of nitrogen flowing through the excess flow valve does not exceed a predetermined flow rate threshold, the excess flow valve is continuously kept in an open state so that nitrogen can be supplied to various nitrogen users along various supply main lines; and When the flow rate of nitrogen flowing through the excess flow valve exceeds a predetermined flow rate threshold, the excess flow valve automatically switches from an open state to a closed state to cut off the supply of nitrogen from the nitrogen supply source to each nitrogen user.

9. The method according to claim 8, wherein: When the flow rate of nitrogen flowing through the excess flow valve is restored to not more than the predetermined flow rate threshold, the excess flow valve automatically returns from the closed state to the open state.

10. The method according to claim 9, wherein: The predetermined flow rate threshold is selected to be equal to or greater than the maximum nitrogen consumption flow rate of all nitrogen users in the nitrogen user group connected to the corresponding main supply line during the same period.

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