Monitoring control system for centrifugal separator

Abstract

The present invention addresses the problem of providing a monitoring control system for a centrifugal separator, the monitoring control system detecting a rapid increase in solid content, thereby making it possible to quickly detect a decrease in separation performance and to prevent equipment failure. The system is provided with a centrifugal separator 2 into which a liquid to be treated is caused to flow and be introduced from an introduction part 20, and in which a separation plate is rotated by an electric motor 21 and the introduced liquid to be treated is separated into sludge and a separated liquid, the separated liquid being discharged to the outside from a separated liquid discharge part 22. The separated liquid discharged from the separated liquid discharge part 22 is introduced into a separated liquid line 3 provided with at least a back pressure valve 31 and a pressure gauge PG. The back pressure valve 31 is adjusted to guide a part of the separated liquid introduced into the separated liquid line 3 to a detection line 4 provided with at least a detection filtering unit 40, a constant flow rate valve 41, and a flowmeter 42. When it is determined that a measurement value by the flowmeter 42 that measures a flow rate adjusted by the constant flow rate valve 41 provided on the downstream side of the detection filtering unit 40 is equal to or less than a predetermined flow rate lower limit threshold, the electric motor 21 is stopped. In this way, the problem is solved.

Description

Monitoring and Control System for a Centrifuge

[0001] The present invention relates to a monitoring and control system for a centrifuge, and more particularly, to a monitoring and control system for a centrifuge that can quickly detect a decrease in separation performance by detecting a rapidly increasing solid content and prevent equipment malfunctions.

[0002] For the purpose of reducing health impacts and improving the atmospheric environment, it has become obligatory to use fuel oil with a sulfur content of 0.5 mass% or less for ships in all seas around the world since January 1, 2020.

[0003] As such fuel oil conforming to these regulations, VLSFO (VERY LOW Sulphur Fuel Oil) is mainly used. VLSFO is mainly classified into paraffinic distillate oil grade VLSFO-DM and aromatic residual oil grade VLSFO-RM according to the fuel oil manufacturing process. VLSFO has a lower kinematic viscosity and density than HSFO (High Sulphur - C heavy oil), has a wider range than conventional fuel oils, and is useful as fuel oil conforming to the regulations.

[0004] However, VLSFO has large variations in the properties of fuel oil due to bunker purging (fuel supply ships), and particularly problems such as sludge generation when different fuel oils are mixed, as well as problems with mixing stability, storage stability, and low-temperature fluidity such as waxing at low temperatures.

[0005] Also, when different VLSFOs of distillate oil type and residual oil type are mixed, there is a risk of a large amount of sludge (solid content) being generated.

[0006] Furthermore, not only in marine fuel oil but also in lubricating oil, there is a possibility that a decrease in the separation performance of the centrifuge may be caused by a large amount of sludge generation.

[0007] Patent Document 1 discloses a method for determining the degree of contamination inside the drum of a centrifuge, which compares a value (theoretical value) with respect to the maximum internal volume of the drum and a measured value (calculated value) of the currently available drum capacity of the drum to determine the degree of contamination and issue warnings and emergency stops.

[0008] Special Publication No. 2023-550810 Publication Patent No. 6931097 Publication

[0009] In a plate-type centrifuge, solid matter is stored inside the rotating body and automatically discharged at set timer intervals. However, if the amount of solid matter in the supplied processing liquid increases rapidly, the rotating body of the centrifuge may become filled with sludge (solid matter) exceeding its capacity. This can lead to poor separation, leakage of accumulated sludge to the clean outlet, and partial retention (segregation) of sludge from the rotating body, potentially resulting in a decrease in the centrifuge's separation performance due to imbalance and equipment malfunction.

[0010] In response to these problems, the technology described in Patent Document 1, even if the volume of sludge relative to the total internal volume decreases, if sludge or the like segregates on the separator (separation plate), it is impossible to avoid a decrease in the separation performance of the centrifuge due to imbalance and malfunctions of the equipment.

[0011] The inventors have developed a new centrifugal separator monitoring and control system that can quickly detect a decrease in separation performance at the centrifugal separator outlet by detecting a rapid increase in solid content, thereby preventing equipment malfunctions and safely stopping operation.

[0012] Therefore, the object of the present invention is to provide a monitoring and control system for a centrifuge that can quickly detect a decline in separation performance by detecting a rapidly increasing amount of solids, thereby preventing equipment malfunction.

[0013] Furthermore, other problems of the present invention will become clear from the following description.

[0014] The above problems are solved by the following inventions.

[0015] 1. The centrifuge (2) is equipped with a structure that allows the liquid to be processed to flow in from the introduction section (20) of the centrifuge (2) and be introduced into the interior, rotates the separation plate (200) of the centrifuge (2) with an electric motor (21) to separate the introduced liquid to be processed into sludge and separated liquid, discharges the sludge from the sludge discharge section (23) and discharges the separated liquid to the outside from the separated liquid discharge section (22), the separated liquid discharged from the separated liquid discharge section (22) is introduced into a separated liquid line (3) equipped with at least a back pressure valve (31) and a pressure gauge (PG), a portion of the separated liquid introduced into the separated liquid line (3) is guided to a detection line (4) equipped with at least a detection filtering unit (40), a constant flow valve (41) and a flow meter (42) by adjusting the back pressure valve (31), and the control unit (5) is connected to at least the flow meter (42) and the electric motor (21). 1. A centrifugal separator monitoring and control system characterized in that the control unit (5) stops the motor (21) when it determines that the value measured by the flow meter (42), which measures the flow rate adjusted by the constant flow valve (41) provided downstream of the detection filtering unit (40), is below a predetermined flow rate lower threshold. 2. The centrifugal separator monitoring and control system according to 1, characterized in that the control unit (5) determines whether the state in which the value measured by the flow meter (42) is below a predetermined flow rate lower threshold has continued for a predetermined detection time, and when it determines that the state has continued for a predetermined detection time, it stops the motor (21).3. The centrifugal separator (2) is provided with a structure in which the liquid to be processed flows in from the introduction section (20) of the centrifugal separator (2) and is introduced into the interior, the separation plate (200) of the centrifugal separator (2) is rotated by an electric motor (21) to separate the introduced liquid to be processed into sludge and separated liquid, the sludge is discharged from the sludge discharge section (23) and the separated liquid is discharged to the outside from the separated liquid discharge section (22), the separated liquid discharged from the separated liquid discharge section (22) is introduced into a separated liquid line (3) which is equipped with at least a back pressure valve (31) and a pressure gauge (PG), a portion of the separated liquid introduced into the separated liquid line (3) is guided to a detection line (4) which is equipped with at least a detection filtering unit (40) and a constant flow valve (41) by adjusting the back pressure valve (31), the detection filtering unit (40) is provided with a detection filter (40B), a pressure gauge P1 is provided upstream of the detection filter (40B) and a pressure gauge P2 is provided downstream of the detection filter (40B), A centrifugal separator monitoring and control system characterized in that the control unit (5) is connected to at least the pressure gauge P1, the pressure gauge P2, and the electric motor (21), and the control unit (5) calculates the differential pressure between the pressure of the pressure gauge P1 and the pressure of the pressure gauge P2, determines whether or not the calculated differential pressure is below a predetermined differential pressure upper threshold, and stops the electric motor (21) if it is determined that the calculated differential pressure is above the predetermined differential pressure upper threshold. 4. The centrifugal separator monitoring and control system according to 3, characterized in that the control unit (5) determines whether or not the state in which the calculated differential pressure is above the predetermined differential pressure upper threshold has continued for a predetermined detection time, and stops the electric motor (21) if it is determined that the state has continued for a predetermined detection time. 5. The centrifugal separator monitoring and control system according to 3 or 4, characterized in that a catch tank (45) is provided downstream of the constant flow valve (41), and an atmospheric vent (46) is provided in the catch tank (45).6. A three-way automatic valve (1) is provided upstream of the introduction section (20) of the centrifuge (2) for the liquid to be processed, which can switch the flow direction of the liquid to be processed to the flow direction of the centrifuge (2) side or the flow direction of the storage tank side of the liquid to be processed, and the control unit (5) is connected to the three-way automatic valve (1), stops the motor (21), and switches the flow direction of the three-way automatic valve (1) on the centrifuge (2) side to the flow direction of the storage tank side of the liquid to be processed, characterized in that the centrifugal separator monitoring and control system is as described in any of 1 to 4 above. 7. A detection filtering unit (40) is composed of a housing (40A) for a filter and a detection filter (40B) housed in the housing, characterized in that the centrifugal separator monitoring and control system is as described in any of 1 to 4 above. 8. A shut-off valve (43) is provided between the detection filtering unit (40) and the constant flow valve (41), characterized in that the centrifugal separator monitoring and control system is as described in any of 1 to 4 above. 9. A monitoring and control system for a centrifugal separator according to claim 7, characterized in that a compressed air introduction line (6) is connected to the detection line (4) downstream of the detection filtering unit (40), and compressed air introduced via the compressed air introduction line (6) is supplied from the downstream side to the upstream side of the detection filtering unit (40) to air-clean the detection filter (40B) in the detection filtering unit (40). 10. A monitoring and control system for a centrifugal separator according to claim 7, characterized in that a cleaning agent introduction line (7) is connected to the detection line (4) downstream of the detection filtering unit (40), and cleaning agent introduced via the cleaning agent introduction line (7) is supplied from the downstream side to the upstream side of the detection filtering unit (40) to clean the detection filter (40B) in the detection filtering unit (40). 11. A monitoring and control system for a centrifugal separator according to claim 10, characterized in that a flow path is provided for introducing the cleaning agent after cleaning the detection filter (40B) into the introduction section (20) of the centrifugal separator (2).12. The monitoring and control system for a centrifugal separator according to 7, characterized in that a compressed air introduction line (6) and a cleaning agent introduction line (7) are connected to the detection line (4) downstream of the detection filtering unit (40), compressed air introduced via the compressed air introduction line (6) is supplied from the downstream side to the upstream side of the detection filtering unit (40) to air-clean the detection filter (40B) in the detection filtering unit (40), and cleaning agent introduced via the cleaning agent introduction line (7) is supplied from the downstream side to the upstream side of the detection filtering unit (40) to clean the detection filter (40B) in the detection filtering unit (40). 13. The monitoring and control system for a centrifugal separator according to 12, characterized in that a flow path is provided for introducing compressed air or cleaning agent after cleaning the detection filter (40B) into the introduction section (20) of the centrifugal separator (2).

[0016] According to the present invention, a monitoring and control system for a centrifuge can be provided that can quickly detect a decrease in separation performance by detecting a rapidly increasing amount of solids, thereby preventing equipment malfunction.

[0017] An explanatory diagram showing the first embodiment. A half-section diagram illustrating an example of the mechanism of a centrifugal separator. A half-section diagram illustrating an example of sludge discharge from a centrifugal separator. A half-section diagram illustrating an example of abnormal sludge deposition in a centrifugal separator. A diagram showing the control flow of the first embodiment. An explanatory diagram showing the filter cleaning configuration in the first embodiment. An explanatory diagram showing the second embodiment. A diagram showing the control flow of the second embodiment.

[0018] Preferred embodiments of the present invention will be described below.

[0019] Figure 1 is an explanatory diagram showing a first embodiment of the present invention. Figure 1 shows an example of a flow rate monitoring system that monitors the state of a centrifuge 2, in which a separation liquid obtained by separating the liquid to be processed by the centrifuge is formed, and a separation liquid line 3 and a detection line 4 branching off from the separation liquid line 3 are formed.

[0020] This embodiment shows an example of separating liquids to be treated, such as fuel oil and lubricating oil.

[0021] The three-way automatic valve 1 is configured to switch the flow direction of the incoming liquid to be treated between the liquid storage tank side (bypass return) and the centrifuge 2 side. The three-way automatic valve 1 can be any valve that can automatically switch the flow direction, such as a solenoid valve or an air valve, and the operating method is not particularly limited. When the three-way automatic valve 1 is switched to the flow direction towards the centrifuge 2, the liquid to be treated flows in from the inlet 20 of the centrifuge 2 and is introduced into the centrifuge 2.

[0022] Figure 2 is a half-sectional view illustrating an example of the mechanism of a centrifugal separator, Figure 3 is a half-sectional view illustrating an example of sludge discharge from a centrifugal separator, and Figure 4 is a half-sectional view illustrating an example of abnormal sludge deposition in a centrifugal separator. In Figures 2 to 4, which will be described later, examples are shown in which the centrifugal separator separates the liquid to be treated into three types: solids (sludge), heavy liquid, and light liquid. However, the centrifugal separator 2 used in this embodiment only needs to be able to separate at least the solids (sludge) and the separated liquid (light liquid). Therefore, the following explanation will be based on the case where the centrifugal separator 2 separates the solids (sludge) and the separated liquid (light liquid).

[0023] As shown in Figures 1 and 2, in the centrifugal separator 2, the separation plate 200 of the centrifugal separator rotates in conjunction with the rotational drive of the electric motor 21, separating the introduced liquid to be processed into solid matter (sludge) and separation liquid.

[0024] The separated liquid from the centrifuge 2 is discharged from the separated liquid discharge section 22 into the separated liquid line 3. As shown in Figures 1, 2, and 3, the solids separated by the centrifuge 2 are stored in the solids storage section 201 inside the centrifuge 2. At this time, the sludge discharge port 203 is closed. After a predetermined time has elapsed, as shown in Figure 3, the valve body 202 at the bottom of the centrifuge 2 opens downward automatically or manually while the separation plate 200 is still rotating, causing the sludge discharge port 203 to open wide. The sludge is then discharged outward from the solids storage section 201 by centrifugal force, and the sludge discharged from the sludge discharge port 203 is discharged to the outside from the sludge discharge section 23.

[0025] As shown in Figure 4, when a liquid to be processed containing a high concentration of solids is supplied to the centrifuge 2, the solids storage section 201 inside the rotating body rapidly fills with solids, reaching the outer end of the separation plate where the liquid is centrifuged. In this case, the separation efficiency may decrease due to turbulence in the flow between the stacked separation plates 200, and the accumulated solids may flow out into the separation liquid line 3 along with the separation liquid as they are eroded along the direction of the fluid flow.

[0026] As shown in Figure 1, the separation liquid line 3 is equipped with at least a back pressure valve 31 and a pressure gauge PG. In the separation liquid line 3, when the separator discharged from the separation liquid discharge section 22 of the centrifuge 2 flows in, the back pressure valve 31 is throttled to increase back pressure and guide a portion of the separation liquid to the detection line 4. The back pressure of the back pressure valve 31 can be adjusted based on the pressure of the pressure gauge PG.

[0027] The detection line 4 includes at least a detection filtering unit 40, a constant flow valve 41, and a flow meter 42.

[0028] The detection filtering unit 40 consists of a filter housing 40A and a detection filter 40B housed within the housing.

[0029] A constant flow valve 41 is provided downstream of the detection filtering unit 40, ensuring a constant flow rate regardless of pressure fluctuations in the separated liquid in the detection line 4.

[0030] Furthermore, a flow meter 42 is provided between the detection filtering unit 40 and the constant flow valve 41, allowing confirmation of whether the constant flow rate is maintained by the constant flow valve 41. In this embodiment, it is preferable to raise the outlet piping downstream of the constant flow valve of the detection line 4 in a substantially vertical direction. The height (head) of the outlet piping can be determined by considering the back pressure of the separated liquid indicated by the pressure gauge PG and the pressure loss of the constant flow valve 41.

[0031] In this embodiment, it is preferable that a shut-off valve 43 is provided between the detection filtering unit 40 and the constant flow valve 41. When the separated liquid is being monitored, the shut-off valve 43 is opened, but it is preferable to keep the shut-off valve 43 closed until the housing 40A is filled with the separated liquid that has branched from the separated liquid line 3 to the detection line 4. Once the housing 40A is completely filled with the separated liquid, detection can be started by opening the shut-off valve 43. The shut-off valve 43 also functions during filter cleaning, which will be described later.

[0032] The control unit 5 is configured to acquire the measured values ​​from the flow meter 42, control the operation of the three-way automatic valve 1 and the electric motor 21 of the centrifugal separator 2, and perform flow rate monitoring.

[0033] Based on Figure 5, the control flow for flow monitoring will be explained with reference to Figure 1. Figure 5 shows an example of the control flow for flow monitoring as a flowchart.

[0034] First, the electric motor is started, and once it reaches its rated speed, operation is initiated (S1).

[0035] Next, the three-way automatic valve 1 is switched to the flow path direction towards the centrifugal separator 2 (S2). Once switched, the liquid to be processed is introduced into the centrifugal separator 2 and centrifuged. The centrifuged separated liquid 30 flows into the separated liquid line 3 via the separated liquid discharge section 22.

[0036] Next, when the separated liquid 30 flows into the separated liquid line 3, the pressure in the pressure gauge PG increases, and the back pressure valve 31 is adjusted according to the pressure value of the pressure gauge PG (S3).

[0037] Next, by adjusting the back pressure valve 31, a portion 30a of the separated liquid 30 that has flowed into the separated liquid line 3 is branched off and flows into the detection line 4. As a result of this inflow, the separated liquid is introduced into the filter housing 40A, and after confirming that the detection start delay timer has elapsed (S4), flow rate monitoring is started.

[0038] Here, by allowing the control unit 5 to set a detection start delay timer (setting unit: sec) from the time the three-way automatic valve 1 is switched to the centrifuge 2 side until monitoring starts, it is possible to prevent false alarms such as "liquid flow starts → immediate alarm". Immediately after the start of liquid flow, the filter housing 40A is not filled with separated liquid, so the flow rate is unstable, which can cause false alarms, and this is useful in preventing that.

[0039] Next, for flow rate monitoring, the control unit 5 pre-sets a predetermined flow rate lower threshold and a predetermined detection time, acquires the measured value from the flow meter 42, and determines whether the state in which the measured value is below the predetermined flow rate lower threshold continues for a predetermined detection time or longer (S5).

[0040] If the monitoring does not continue (NO in S5), the flow rate monitoring in S5 will be repeated.

[0041] On the other hand, if the phenomenon continues (YES in S5), it is considered abnormal sludge deposition and an alarm is issued (S6).

[0042] When abnormally precipitated sludge (solid matter) flows out to the separation liquid side, it accumulates on the detection filter 40B inside the filter housing 40A, causing the flow rate of the flow meter 42 downstream of the detection filtering unit 40 to decrease. Therefore, unless this is a false detection, the flow rate will remain below the lower limit threshold for a predetermined detection time or longer, and abnormal sludge precipitation can be detected based on the measurement value of the flow meter 42. As the detection filter 40B, metal media such as sintered metal, laminated sintered metal, wedge wire screen, notch wire, spring filter, or ceramic filter can be used, and the filter can be cleaned by backflow with compressed air.

[0043] Next, simultaneously with the alarm sounding, the three-way automatic valve 1 is switched to the flow path on the fuel oil storage tank side to stop the supply of the liquid to be processed to the centrifugal separator 2, and at the same time the power supply to the electric motor 21 of the centrifugal separator 2 is shut off (S7), causing the centrifugal separator 2 to be stopped in an emergency.

[0044] By controlling in this way, it is possible to quickly detect a decrease in the separation performance of the centrifuge 2. As a result, it is possible to quickly recover the decrease in the separation performance and prevent the occurrence of equipment failures.

[0045] In the above description, in the determination of S5, it is determined whether or not the state where the measured value is below the predetermined flow rate lower limit threshold continues for a predetermined detection time or longer. However, from the viewpoint of quickly detecting a decrease in separation performance and preventing equipment failures, the determination of whether or not it continues for a predetermined detection time or longer may not be necessary. This is because the determination based on the detection time is for the purpose of preventing false detection.

[0046] FIG. 6 is a diagram for explaining an example of cleaning the detection filter in the flow rate monitoring system of FIG. 1. In FIG. 6, the same reference numerals as those in FIG. 1 denote the same parts, and the description thereof is omitted.

[0047] FIG. 6 shows an example in which a compressed air introduction line 6 and a cleaning agent introduction line 7 are formed in the flow rate monitoring system of FIG. 1.

[0048] First, the cleaning via the compressed air introduction line 6 will be described. In this aspect, compressed air is introduced from the back side of the detection filtering unit 40 through the compressed air introduction line 6 to clean the filter, and after the filter is cleaned, it is configured to be introduced from the introduction part 20 side of the centrifuge 2. In the present embodiment, the timing of filter cleaning of the detection filter 40B is preferably, for example, immediately after the solid content discharge process of the centrifuge 2 shown in FIG. 3. By periodically cleaning the filter, the monitoring accuracy can be maintained.

[0049] The compressed air from the compressor (not shown) that generates the compressed air only needs to be at a pressure sufficient to clean the filter. As shown in Figure 6, by opening shut-off valve 61, then shut-off valve 62, and further closing shut-off valve 43 of the detection line 4, compressed air is introduced from the back of the detection filter 40B via the compressed air introduction line 6, forming a flow path for cleaning the filter. After the filter has been cleaned, since shut-off valve 62 is open, a flow path is formed for the compressed air to be introduced into the introduction section 20 of the centrifugal separator 2. In addition, by closing shut-off valve 43 of the detection line 4, compressed air is prevented from flowing out to the downstream side of the detection filtering unit 40 of the detection line 4, ensuring that the filter is cleaned properly.

[0050] Furthermore, when compressed air is introduced, the check valve 44 can block the flow of compressed air to the junction of the detection line 4 and the separated liquid line 3. In this embodiment, a manual valve (not shown) may be provided upstream of the check valve 44 on the detection line to block the inlet of the detection line 4 that branches off from the separated liquid line 3. This prevents compressed air from flowing into the entire detection line 4 before and after passing through the centrifugal separator when compressed air is introduced, and allows compressed air to be introduced only to the detection filtering unit 40.

[0051] Furthermore, a check valve 63 is provided near the confluence of the flow paths where the compressed air from the compressed air introduction line 6 reaches the three-way automatic valve 1 and the introduction section 20 of the centrifugal separator 2. By providing this check valve 63, the inflow of the liquid to be processed can be prevented during normal operation.

[0052] Next, cleaning via the cleaning agent introduction line 7 will be described. The cleaning agent is introduced from the rear of the detection filtering unit 40 via the cleaning agent introduction line 7, and the cleaning agent after cleaning the filter is configured to be introduced from the introduction section 20 side of the centrifuge 2. The cleaning agent introduced from the introduction section 20 of the centrifuge 2 is discharged from the centrifuge 2 as discharged sludge. By introducing the cleaning agent after cleaning the detection filter 40B into the centrifuge 2, it is possible to clean not only the detection filter 40B but also the centrifuge 2.

[0053] Oil-soluble cleaning agents containing paraffin-based or aromatic solvents are preferred as cleaning agents, and water-soluble solvents containing surfactants, glycol solvents, chelating agents, etc., which have a low environmental impact, can also be used. For example, oil-soluble or water-soluble cleaning agents (product name: Unizol series) manufactured by Nippon Yuka Kogyo Co., Ltd. can be used.

[0054] In this embodiment, it is preferable to clean the detection filter 40B immediately after the solid matter discharge process of the centrifuge 2 shown in Figure 3. Regular filter cleaning helps maintain monitoring accuracy.

[0055] In the cleaning agent introduction line 7, the cleaning agent can be supplied from behind the detection filter 40B via a supply pump 71 from a cleaning agent tank (not shown) to clean the filter. The cleaning agent is supplied from behind the detection filter 40B by closing the shut-off valve 43 and opening the shut-off valves 72 and 62. Since the shut-off valve 62 is open, the cleaning agent used to clean the filter can form a flow path to be introduced into the introduction section 20 of the centrifugal separator 2. Because the shut-off valve 43 of the detection line 4 is closed, the cleaning agent introduced from the cleaning agent introduction line 7 is prevented from flowing downstream of the detection line 4, ensuring that the filter is cleaned with the cleaning agent.

[0056] Furthermore, when introducing the cleaning agent, the check valve 44 can block the flow of the cleaning agent to the junction of the detection line 4 and the separated liquid line 3. In this embodiment, a manual valve (not shown) may be provided upstream of the check valve 44 on the detection line to block the inlet of the detection line 4 that branches off from the separated liquid line 3. This prevents the cleaning agent from flowing into the entire detection line 4 before and after passing through the centrifugal separator when introducing the cleaning agent, and allows the cleaning agent to be introduced only into the detection filtering unit 40.

[0057] Furthermore, a check valve 63 is provided near the confluence of the flow paths from the detergent introduction line 7 to the introduction section 20 of the three-way automatic valve 1 and the centrifugal separator 2. By providing this check valve, it is possible to prevent the liquid to be treated from flowing into the detergent introduction line 7 during normal operation.

[0058] In this embodiment, either the compressed air introduction line 6 or the detergent introduction line 7 may be provided, or both may be provided simultaneously. If both are provided simultaneously, it is preferable to differentiate the timing of cleaning with compressed air and cleaning with detergent. For example, cleaning with compressed air may be performed daily, while cleaning with detergent may be performed once every few days or once a week.

[0059] Furthermore, the compressed air introduction line 6 and the cleaning agent introduction line 7 may be installed when cleaning the flow rate monitoring system. For example, they can be connected by providing a connection port in the piping upstream of the shut-off valve 43 downstream of the detection filtering unit 40. Alternatively, a connection port can be provided downstream of the check valve 44 upstream of the detection filtering unit 40, and a connection port can be provided at the confluence of the flow paths leading to the introduction section 20 of the three-way automatic valve 1 and the centrifugal separator 2. By connecting these connection ports, a flow path for cleaning liquid and compressed air can be formed, allowing the compressed air and cleaning agent after cleaning the filter to be introduced to the introduction section 20 of the centrifugal separator 2.

[0060] In this embodiment, instead of providing a supply pump 71 in the detergent introduction line 7, a compressed air supply device (not shown) for supplying detergent may be separately installed in the detergent tank (not shown) to pressurize the detergent tank and supply the detergent. Alternatively, the compressor of the compressed air introduction line 6 may be connected to the detergent tank to pressurize the tank.

[0061] In this embodiment, when using a cleaning agent from the cleaning agent introduction line 7, after cleaning the filter, the used cleaning agent may be merged into the sludge flow path discharged from the sludge discharge section 23 of the centrifugal separator 2 shown in Figure 6, so as not to pass through the inside of the centrifugal separator 2. For example, in the cleaning agent introduction line 7, cleaning agent is supplied from a cleaning agent tank (not shown) via a supply pump 71 from behind the detection filter 40B to clean the filter. The used cleaning agent can then be discharged to the sludge discharge section 23 side without passing through the introduction section 20 of the centrifugal separator 2 by closing the shut-off valve 62 and opening the shut-off valve 64.

[0062] Furthermore, in this embodiment, compressed air from the compressed air introduction line 6, after cleaning the filter, may be introduced into the flow path that merges with the sludge discharge section 23.

[0063] The shut-off valves 62 and 64 may be configured to switch between, for example, cleaning with the cleaning agent from the cleaning agent introduction line 7 and cleaning with compressed air from the compressed air introduction line 6. In this embodiment, it is preferable to configure the system so that one of the shut-off valves 62 and 64 is open and the other is closed.

[0064] Figure 7 is an explanatory diagram showing an example of a second embodiment. Figure 7 shows an example of a pressure monitoring system that monitors the state of a centrifuge, in which a separated liquid obtained by separating the liquid to be processed by the centrifuge is formed, and a detection drain line branching off from the separated liquid line is formed. In Figure 7, the same reference numerals as in Figure 1 are the same components, so their explanation is omitted.

[0065] In the case of a pressure monitoring system, the detection filtering unit 40 has a pressure gauge P1 upstream of the detection filter 40B and a pressure gauge P2 downstream of it. The control unit 5 calculates the pressure difference between the pressure of pressure gauge P1 and the pressure of pressure gauge P2, and performs pressure monitoring control based on the calculated pressure difference.

[0066] A catch tank 45 is provided downstream of the constant flow valve 41, and an atmospheric vent 46 is provided in the catch tank 45, allowing the downstream side to be open to the atmosphere, which causes the pressure gauge P2 to decrease. Therefore, when the valve is blocked, the pressure gauge P1 will be approximately the pressure indicated by the pressure gauge PG, and the pressure gauge P2 will be the atmospheric pressure, resulting in a large pressure difference. As a result, a pressure difference is easily generated and can be easily detected. In this embodiment, it is preferable to provide a pump (not shown) downstream of the catch tank 45.

[0067] In this embodiment, Figure 8 shows the control flow when pressure monitoring is performed instead of flow rate monitoring as shown in Figure 5.

[0068] In Figure 8, pressure monitoring is performed. For pressure monitoring, the decision at S5 shown in Figure 5 becomes the decision at S8. Otherwise, the control is the same as in the case of flow rate monitoring.

[0069] The control unit 5 pre-sets an upper limit threshold for the differential pressure between the pressure gauge P1 and the pressure gauge P2. It also pre-sets a predetermined detection time.

[0070] As shown in Figure 8, it is determined whether the condition of being above a preset differential pressure upper threshold has been maintained for a preset detection time or longer (S8).

[0071] If the monitoring is not continuing (NO in S8), the pressure monitoring in S8 is continued. On the other hand, if the monitoring is continuing (YES in S8), it is considered abnormal sludge deposition and an alarm is issued (S6).

[0072] Next, similar to the flow rate monitoring, an alarm is issued, and simultaneously, process S7 is executed, and the centrifuge is shut down as an emergency.

[0073] When precipitated sludge (solid matter) flows out to the separation liquid side, it accumulates on the detection filter in the filter housing, creating a difference in pressure between the pressure gauges before and after the filter. The differential pressure calculated from the difference between the pressure gauge P1 before the filter and the pressure gauge P2 after the filter increases. If this is not a false detection, the differential pressure will exceed the upper threshold, and this condition will continue for longer than the detection time, thus detecting sludge precipitation. On the other hand, large-diameter particles, which are about the same size as or smaller than the filter opening, are centrifuged with high efficiency, so there is no material captured by the filter, no pressure difference is created before and after the filter, and the centrifuge continues to operate.

[0074] By controlling the system in this way, a decrease in separation performance can be quickly detected, and as a result, the state of reduced separation performance can be quickly restored, preventing equipment malfunctions.

[0075] In the above explanation, the judgment in S8 is made to determine whether the measured value has been above a predetermined differential pressure upper threshold for a predetermined detection period or longer. However, it is not necessary to make a judgment on whether or not this condition has been continuing for a predetermined detection period or longer.

[0076] In the pressure monitoring of this embodiment, filter cleaning can be performed in the same way as in the case of Figure 6, so its explanation will be omitted.

[0077] According to the present invention, conventionally, centrifuges would become completely clogged with sludge (solid matter), and in some cases, the abnormal precipitation of sludge would only be noticed after a malfunction occurred during operation. However, with the present invention, "filter clogging in a short time" makes it possible to quickly detect equipment malfunctions.

[0078] Furthermore, factors that reduce the separation performance of a centrifugal separator are not limited to the precipitation of sludge exceeding expectations, but also include various other factors such as increased processing flow rate, excessively long sludge discharge timer intervals, decreased processing temperature, and increased viscosity of the processing liquid. Since the decrease in separation performance is detected by this invention, it becomes possible to detect inappropriate operating conditions and settings, enabling stable operation of the centrifugal separator.

[0079] 1: Three-way automatic valve 2: Centrifugal separator 20: Inlet 21: Electric motor 22: Separation liquid discharge section 23: Sludge discharge section 200: Separation plate 201: Solids storage section 202: Valve body 203: Sludge outlet 3: Separation liquid line 30: Separation liquid 30a: Part of the separation liquid 31: Back pressure valve PG: Pressure gauge 4: Detection line 40: Detection filtering unit 40A: Housing 40B: Detection filter P1: Pressure gauge P2: Pressure gauge 41: Constant flow valve 42: Flow meter 43: Shut-off valve 44: Check valve 45: Catch tank 46: Vent for atmospheric release 5: Control unit 6: Compressed air inlet line 61: Shut-off valve 62: Shut-off valve 63 :non-return valve

Claims

1. The centrifuge (2) is equipped with a structure in which the liquid to be processed is introduced into the centrifuge (2) from the inlet (20), the separation plate (200) of the centrifuge (2) is rotated by an electric motor (21) to separate the introduced liquid to be processed into sludge and separated liquid, the sludge is discharged from the sludge discharge section (23), and the separated liquid is discharged to the outside from the separated liquid discharge section (22), the separated liquid discharged from the separated liquid discharge section (22) is introduced into a separated liquid line (3) equipped with at least a back pressure valve (31) and a pressure gauge (PG), a portion of the separated liquid introduced into the separated liquid line (3) is guided to a detection line (4) equipped with at least a detection filtering unit (40), a constant flow valve (41), and a flow meter (42) by adjusting the back pressure valve (31), and the control unit (5) is connected to at least the flow meter (42) and the electric motor (21). The centrifugal separator monitoring and control system is characterized in that the control unit (5) stops the electric motor (21) when it determines that the value measured by the flow meter (42), which measures the flow rate adjusted by the constant flow valve (41) provided downstream of the detection filtering unit (40), is below a predetermined lower limit threshold.

2. The control unit (5) determines whether the state in which the value measured by the flow meter (42) is below a predetermined flow rate lower threshold has continued for a predetermined detection time, and if it determines that the state has continued for the predetermined detection time, it stops the electric motor (21), characterized in that the centrifugal separator monitoring and control system according to claim 1.

3. The centrifuge (2) is equipped with a structure in which the liquid to be treated flows in from the introduction section (20) of the centrifuge (2) and is introduced into the interior, the separation plate (200) of the centrifuge (2) is rotated by an electric motor (21) to separate the introduced liquid to be treated into sludge and separated liquid, the sludge is discharged from the sludge discharge section (23) and the separated liquid is discharged to the outside from the separated liquid discharge section (22), the separated liquid discharged from the separated liquid discharge section (22) is introduced into a separated liquid line (3) equipped with at least a back pressure valve (31) and a pressure gauge (PG), and a portion of the separated liquid introduced into the separated liquid line (3) is guided to a detection line (4) equipped with at least a detection filtering unit (40) and a constant flow valve (41) by adjusting the back pressure valve (31). A detection filtering unit (40) is provided with a detection filter (40B), a pressure gauge P1 is provided upstream of the detection filter (40B), and a pressure gauge P2 is provided downstream of the detection filter (40B), a control unit (5) is connected to at least the pressure gauge P1, the pressure gauge P2, and the motor (21), and the control unit (5) calculates the differential pressure between the pressure of the pressure gauge P1 and the pressure of the pressure gauge P2, determines whether or not the calculated differential pressure is below a predetermined differential pressure upper threshold, and stops the motor (21) if it is determined that the calculated differential pressure is above the predetermined differential pressure upper threshold.

4. The control unit (5) determines whether the calculated differential pressure remains above a predetermined differential pressure upper threshold for a predetermined detection period, and if it determines that the condition has continued for the predetermined detection period, it stops the electric motor (21), characterized in that it is the monitoring and control system for a centrifugal separator according to claim 3.

5. A monitoring and control system for a centrifugal separator according to claim 3 or 4, characterized in that a catch tank (45) is provided downstream of the constant flow valve (41), and an atmospheric vent (46) is provided in the catch tank (45).

6. A three-way automatic valve (1) is provided upstream of the introduction section (20) of the centrifuge (2) for the liquid to be processed, which can switch the flow of the liquid to be processed in the direction of the flow path on the centrifuge (2) side or the flow path on the storage tank side of the liquid to be processed, and the control unit (5) is connected to the three-way automatic valve (1), and stops the electric motor (21) and switches the flow path direction of the three-way automatic valve (1) on the centrifuge (2) side to the flow path on the storage tank side of the liquid to be processed, characterized in that the centrifugal separator monitoring and control system is as described in any one of claims 1 to 4.

7. The monitoring and control system for a centrifuge according to any one of claims 1 to 4, characterized in that the detection filtering unit (40) comprises a housing for a filter (40A) and a detection filter (40B) housed within the housing.

8. A centrifugal separator monitoring and control system according to any one of claims 1 to 4, characterized in that a shut-off valve (43) is provided between the detection filtering unit (40) and the constant flow valve (41).

9. The centrifugal separator monitoring and control system according to claim 7, characterized in that a compressed air introduction line (6) is connected to the detection line (4) downstream of the detection filtering unit (40), and compressed air introduced via the compressed air introduction line (6) is supplied from the downstream side to the upstream side of the detection filtering unit (40) to air-clean the detection filter (40B) inside the detection filtering unit (40).

10. The monitoring and control system for a centrifuge according to claim 7, characterized in that a cleaning agent introduction line (7) is connected to the detection line (4) downstream of the detection filtering unit (40), and the cleaning agent introduced via the cleaning agent introduction line (7) is supplied from the downstream side to the upstream side of the detection filtering unit (40) to clean the detection filter (40B) inside the detection filtering unit (40).

11. The monitoring and control system for a centrifuge according to claim 10, characterized in that a channel is provided for introducing the cleaning agent used after cleaning the detection filter (40B) into the inlet (20) of the centrifuge (2).

12. The monitoring and control system for a centrifugal separator according to claim 7, characterized in that a compressed air introduction line (6) and a cleaning agent introduction line (7) are connected to the detection line (4) downstream of the detection filtering unit (40), compressed air introduced via the compressed air introduction line (6) is supplied from the downstream side to the upstream side of the detection filtering unit (40) to air-clean the detection filter (40B) inside the detection filtering unit (40), and a cleaning agent introduced via the cleaning agent introduction line (7) is supplied from the downstream side to the upstream side of the detection filtering unit (40) to clean the detection filter (40B) inside the detection filtering unit (40).

13. The monitoring and control system for a centrifuge according to claim 12, characterized in that a flow path is provided for introducing compressed air or cleaning agent after cleaning the detection filter (40B) into the inlet (20) of the centrifuge (2).

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