JPH02132017A - Powder air transfer equipment - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is applicable to powders that are harmful to the human body, such as radioactive incineration ash generated from nuclear power plants, and powders that contain metal foreign substances such as wires. The present invention relates to a suitable powder pneumatic transfer facility.

[Prior Art] As described in Japanese Patent Application No. 61-106406, a conventional device consists of a closed loop with a transfer pipe centered around a blower, through which air is passed, and during this closed loop, air is transferred from a hopper to a rotary leaf feeder. Powder is supplied in a fixed amount, transferred while ensuring an appropriate air-powder mixing ratio, and then separated and recovered from the air using a cyclone and filter. or,
To prevent powder from scattering, the discharge side of the blower is connected to HVAC.
It is also designed to maintain negative pressure in a controlled manner. [Problem M to be solved by the invention] However, the above conventional technology had the following problems. ■ When the amount of powder supplied by the rotary feeder changes, the mixing ratio of powder and air changes, and if the mixing ratio becomes too high (i.e., the amount of powder becomes too large compared to the amount of air), pressure loss increases. This causes problems such as increased load on blowers, cyclones, and filters, and ash accumulation in transfer piping (particularly in horizontal sections).

■ If a blockage occurs in the middle of the transfer pipe, positive pressure will develop inside the transfer pipe where air is sent by the blower, and powder may flow outside.

■ A rotary feeder is used to feed powder, but the powder fed by this method generally contains a lot of foreign matter such as wire and lumpy powder. These foreign objects are likely to get caught and cause sticks. The purpose of the present invention is to maintain an appropriate mixing ratio of powder and air at all times, to prevent positive pressure from occurring in the transfer piping even if a blockage occurs, and to prevent metallic foreign objects from entering the transferred powder. An object of the present invention is to provide an air transfer facility for powder that can reduce the possibility of contamination.

[Means for Solving the Problems] The powder air transfer equipment of the present invention includes, in order from the upstream side as viewed in the air flow direction, a suction nozzle that can be raised and lowered in a suction hopper;
A lift system consisting of a transfer pipe, a cyclone for powder separation and recovery, and a blower connected in series, and the suction opening of the suction nozzle is positioned near the surface of the powder stored in the suction hopper, and the suction nozzle is raised and lowered in a horizontal manner. The present invention is characterized in that the powder in the suction hopper is transferred through the transfer pipe together with the air sucked into the suction opening of the suction nozzle.

[Function] By raising and lowering the suction nozzle and maintaining an appropriate relative positional relationship between the suction nozzle and the powder surface in the suction hopper, the specified amount of powder is always maintained even if the amount of powder supplied to the suction hopper fluctuates. Air transfer of powder is possible with the powder-air mixing ratio.
The problems of increased load on blowers, cyclones, filters and powder build-up in transfer piping are eliminated. In addition, the entire system is maintained at a negative or positive level by the blower, and even if a blockage occurs, a positive pressure will not be created, so that scattering of powder to the outside of the system can be prevented. In addition, by utilizing the difference in the air speed at which the powder and foreign metal scraps are stirred up, the air flow rate is controlled so that the powder is transferred but the metal objects mixed in with it are not. becomes possible.

[Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 in the case of handling incineration ash generated at a nuclear facility. Incineration ash is generated from the incinerator 1 and the ceramic filter 2 which is the vent treatment device of the incinerator 1, is transferred horizontally by the ash transfer conveyor 3, is coarsely sieved by the vibrating sieve 4, and the ash passing through the mesh is transferred horizontally by the ash transfer conveyor 3. Does it suck? The solids on the sieve are collected in the drum 13. The conveyor 3, the vibrating sieve 4, and the suction hopper 5 are of a closed type surrounded by a closed wall. The ash remaining on the suction hopper 5 is
By starting the blower 11, the air is sucked from the suction nozzle 6 as described later, passes through the transfer pipe 20, is collected by the cyclone 8 and the bag filter 9, and is collected in the receiving hopper 12. In the bag filter 9, the collected ash is removed by backwashing with air. The suction air that has exited the bag filter 9 is further collected with a trace amount of ash by an IIEPA filter 1o, and is exhausted to the HVAC (air conditioning system duct) through a blower 11.

A suction nozzle 6 provided in the suction hopper 5 is connected to an inner cylinder 6.
1 and an outer cylinder 62, forming a double cylinder with an open bottom end. When the blower 11 is operated, suction air flows from IIVAc through the flow rate detector 16 and the flow rate control valve 17, and then passes through the suction nozzle 6.
It passes between the inner cylinder 6■ and the outer cylinder 6■, goes around the lower end of the nozzle 6, is sucked into the inner cylinder 61, passes through the bellows 21, the transfer piping 20, and is sucked into the cylinder 61. It is sucked into the blower 11 through the Ron 8, the bag filter 9, and the Heba filter 10, and from there the HVA
Exhausted to C. The lower end of the suction nozzle 6 is connected to the hopper 5.
The electric motor 1 for lifting is located near the surface of the ash that has accumulated in the
Therefore, the ash is sucked into the inner cylinder 6 of the nozzle 6 along with the above-mentioned suction air flow, and is conveyed to the above-mentioned cyclone 8 through the transfer pipe 20. The electric motor 15 for lifting is connected to the transfer pipe 2 on the inlet side of the cyclone 8.
The positioning of the suction nozzle 6 is controlled in accordance with a signal from a pressure detector 14 provided at 0. That is, when the pressure inside the transfer pipe 20 detected by the detector 14 increases, the suction nozzle 6 is lowered, and conversely, when it decreases, the suction nozzle 6 is raised to control the pressure to an appropriate value. . That is, the increase in pressure means that the pressure loss from the suction nozzle 6 to the pressure detector 14 has decreased, which means that the amount of ash transferred has decreased. Therefore, the suction nozzle 6 is lowered to increase the amount of ash transferred. Conversely, if the pressure decreases, it means that the amount of ash being transferred is too large, so the suction nozzle 6 is raised to reduce the amount of ash being transferred. The flow rate of the suction air is controlled by a flow rate control valve 17 based on a signal from a flow rate detector 16. The purpose of this is to separate metal foreign substances mixed into the ash by keeping the flow velocity in the transfer pipe at an appropriate value.

FIG. 3 shows the relationship between whether or not ash or metal foreign matter is transferred through the transfer pipe depending on the flow velocity in the transfer pipe. As can be seen from this figure, in order to transfer only ash from the hopper 15 and not transfer metal foreign matter, it is necessary to
It is appropriate to choose a flow rate of m/see. ioI
At a flow rate of less than 11 m/sec, some of the ash is deposited on the horizontal portion of the transfer pipe, and at a flow rate of 18 m/sec or more, small foreign objects such as pins and clips are also partially transferred. Suction hopper 5
The metal foreign matter remaining at the bottom of the container is discharged by opening the discharge damper 7 and collected in the collection box 18.

FIG. 3 shows a second embodiment. This embodiment differs from the previous embodiment in that the collection destination of the ash collected in the bag filter 9 is changed from the receiving hopper 12 to the suction hopper 5. If the ash separated from the air is collected by falling through the collection pipe by gravity, it is necessary to maintain the slope of the collection pipe at least equal to or higher than the angle of repose of the ash, and the slope needs to be 70". Therefore, When attempting to collect both the ash collected by the cyclone 8 and the bag filter 9 into the receiving hopper 12 as shown in FIG. 12, which requires a large space in the height direction and imposes extremely large layout constraints.In order to avoid such disadvantages, in the second embodiment, as shown in FIG. The ash collected by the bag filter 9 is
The waste is collected again into the suction hopper 5 through the collection pipe 22 having an inclination of 70° or more, forming a closed loop. It can be expected that the collection efficiency of the Niikron 8 is about 95%, and even if the remaining 5% is collected by the bag filter 9 and returned to the suction hopper 5, there is little effect on the overall transfer efficiency, and the bag filter 9 is transferred to the receiving hopper. The advantage in terms of layout is that they can be installed farther apart than 12. FIG. 4 shows a third embodiment. Since ash is hygroscopic, dehumidification measures are required when storing it in the receiving hopper 12 for a long period of time. Therefore, dry air is injected into the receiving hopper 12 for dehumidification. In this embodiment, the bag filter 9 and the HEPA filter 10 are also used as a filter for removing ash accompanying the dry air injected into the receiving hopper 12. When the ash is not transferred from the hopper 5 to the cyclone 8, the stop valve 19 is closed and dry air is introduced into the receiving hopper 12 to keep the inside of the receiving hopper 12 in a dry state. This dry air entrains some of the ash in the receiving hopper 12 and is transferred to the cyclone 8 → bag filter 9 → heba filter 10 → blower 1.
The ash guided through the route 1→HVAC is collected by a bag filter 9 and a hepa filter 10.

In the above embodiments, the suction nozzle 6 has a double-tube structure, but instead, a plurality of individual cylinders are provided close to each other, and the suction nozzle 6 is provided with a plurality of separate cylinders close to each other, and the suction nozzle 6 is provided with a plurality of separate cylinders close to each other. The suction nozzle may be configured to suck air into another cylinder from the lower end, or a single cylinder may be used as a suction nozzle, and the air guided into the suction hopper 5 may be sucked from the lower end of the suction nozzle. It is also possible to In any case, the suction opening of the suction nozzle is positioned near the surface of the accumulated powder in the suction hopper 5, so that the powder in the hopper is sucked together with air into the suction nozzle and transferred through the transfer piping. Of course.

[Effects of invention According to the present invention, there are the following effects.

■ Since it is possible to obtain an appropriate mixing ratio of powder and air,
Stable air transfer of powder is possible.

It is particularly effective in preventing clogging of the transfer pipe and prevention of ash accumulation in the transfer pipe.

■ Because it is a suction method, negative pressure operation is possible at all times.Since the suction method is performed by a blower installed at the downstream end of the system, it is possible to maintain the metal body in the system at a constant negative pressure, and if powder transfer Even if the transfer piping or the like is clogged, positive pressure will not be created inside the system, so powder can be prevented from scattering outside the system.

■ Since it is possible to prevent relatively large foreign objects from being sucked in when suctioning the powder with the suction nozzle in the pre-transfer stage, the potential for problems such as foreign objects getting caught on the downstream side is reduced.

[Brief explanation of drawings]

Figure 1 is an equipment configuration diagram of the first embodiment of the present invention, Figure 2 is a diagram showing the results of a transfer test of ash and metal foreign matter, Figures 3 and 4 are
The figures are diagrams showing tooth arrangement configurations of a second embodiment and a third embodiment of the present invention, respectively. 1... Incinerator 2... Ceramic filter 3... Ash transfer conveyor 4... Vibrating sieve machine 5...
・Suction hopper 6...Suction nozzle 7...Discharge tank 8...Cyclone 9...Bag filter
10...Hepa filter 11...Blower 1
2...Receiving hopper 13...Drum can 14...
Pressure detector 15... Lifting motor 16... Flow rate detector 17... Flow rate control well 18... Recovery box 19... Stop valve

Claims (1)

[Claims] 1. A suction hopper comprising a suction nozzle that can be raised and lowered in a suction hopper, a transfer pipe, a cyclone for separating and recovering powder, and a blower connected in series from the upstream side as viewed in the air flow direction. The suction opening of the suction nozzle is positioned near the surface of the powder stored in the suction hopper. 1. Powder air transfer equipment characterized in that the powder is configured to be transferred through a transfer pipe. 2. The powder pump according to claim 1, further comprising a detector for detecting the pressure within the transfer pipe, and wherein the elevating means controls the elevating and lowering of the suction nozzle so as to maintain the detected pressure at a predetermined value. Air transfer equipment. 3. The powder air transfer equipment according to claim 1 or 2, further comprising means for controlling the flow rate of suction air to the suction nozzle so as to maintain the air flow velocity in the transfer piping at a predetermined value. 4 The suction nozzle forms a double cylinder consisting of an inner cylinder and an outer cylinder with an open bottom end, and is configured so that the air passing between the inner cylinder and the outer cylinder goes around the lower end and is sucked into the inner cylinder. 4. The powder pneumatic transfer equipment according to claim 1, 2 or 3.