JP2021089093A - Cart equipped with elevation mechanism, and method of attaching/detaching constant feeder using the same - Google Patents

Abstract

To provide a cart that allows a worker to easily carry out replacing work of a constant feeder in a short time.SOLUTION: A cart 50 for use in replacing a constant feeder attached to the bottom of a silo belonging to a feeding facility or the like for feeding solid fuel or a desulfuring agent into a combustor of a circulation fluidized bed boiler, is characterized by comprising a supporting part equipped with an elevation mechanism that supports the constant feeder kept in a state of maintaining an attitude allowing it to be attached to the silo.SELECTED DRAWING: Figure 5

Description

The present invention relates to a trolley provided with an elevating mechanism used when inspecting and replacing a metering feeder attached to the bottom of a silo, and a method for attaching and detaching the metering feeder using the carriage.

As described in Patent Document 1, for example, the Circulating Fluidized Bed boiler collects solid fuel such as particulate fluidized sand or coal that has ejected from the upper part of a furnace (combustor) together with combustion exhaust gas with a cyclone. It has a structure to return to the furnace again, and the gas speed (empty tower speed) in the furnace can be increased as compared with the fluidized bed boiler, so that the fluidized sand or solid fuel in the furnace can be increased. It becomes possible to improve the combustion efficiency by activating the mixing with the combustion air.

Further, in a general boiler, the combustion temperature in the furnace is 1,400 to 1,500 ° C, whereas in a circulating fluidized bed boiler, the combustion temperature can be suppressed to about 800 to 900 ° C, so that it is for combustion. it is possible to suppress the formation of thermal NO _X generated by the high temperature oxidation air. Further, in the circulating flow layer boiler, _{by supplying limestone powder (calcium carbonate (CaCO 3} )) as a desulfurizing agent into the furnace, the desulfurization reaction shown in the following reaction formula 1 can be generated in the furnace. A flue gas desulfurization device for reducing the SOx concentration in the combustion exhaust gas discharged from the circulating flow layer boiler becomes unnecessary, or a simplified desulfurization device can be used.
[Reaction formula 1]
CaCO ₃ + SO ₂ + 1 / 2O ₂ → CaSO ₄ + CO ₂

As a method of supplying the above-mentioned limestone powder to the furnace of a circulating fluidized bed boiler, for example, as described in Patent Document 2, the limestone powder in the flexible container bag is first charged into a hopper and stored by pumping from the hopper. Transfer the limestone powder to the silo. Then, a method of quantitatively supplying the silo from the bottom of the silo into the furnace using a quantitative feeder is common.

Japanese Unexamined Patent Publication No. 6-281108 Japanese Unexamined Patent Publication No. 2019-105399

In the normal operation of the circulating fluidized bed boiler, the supply amount of limestone powder is controlled so as to be a constant ratio to the supply amount of solid fuel such as coal, and the supply amount of limestone powder is adjusted according to the SOx concentration in the exhaust gas. Is controlled. Therefore, the quantitative feeder of the limestone powder is required to quantitatively supply the limestone powder over a long period of time. However, a positive displacement quantitative feeder represented by a rotary feeder, a table feeder, a screw feeder, etc. drives a rotating portion such as a rotor that quantitatively cuts out powder or granular material, a housing portion that accommodates the rotating portion, and the rotating portion. Since it is composed of a drive unit such as a motor, the contact portion with the powder or granular material may be worn while the operation is continued, and it may be difficult to supply it quantitatively (also referred to as cutting out). Therefore, in general, it is necessary to replace the internal parts such as the rotating part at a frequency of about once every 6 months, and to regularly inspect and maintain the parts.

Since the metering feeder is attached to the bottom of the silo as described above, it is extremely difficult to replace only the internal parts during the above replacement and maintenance. Therefore, normally, after removing the metering feeder from the silo in the assembled state, a separately prepared spare metering feeder in the assembled state is attached, and the removed metering feeder is repaired by overlaying or the like. Is being done. As described above, in the replacement and maintenance of the metering feeder attached to the bottom of the silo, it is necessary to perform the attachment / detachment work of replacing the metering feeder with a spare metering feeder in the assembled state.

Conventionally, when the metering feeder attached to the bottom of the silo is attached and detached in the assembled state as described above, it is necessary to suspend the metering feeder by using a chain block or the like. At that time, as described above, since the metering feeder was attached to the bottom of the silo, it could not be hung directly below, and it was necessary to work while hanging it in a balanced manner from two places diagonally above. Therefore, it takes time and effort to attach and detach the conventional quantitative feeder.

In addition, when replacing the quantitative feeder for limestone, it is naturally necessary to stop the limestone powder supply equipment, and if this stop period is long, the SOx concentration in the combustion exhaust gas discharged from the circulating fluidized bed boiler will increase. There is a risk, and in some cases it may be necessary to stop the operation of the boiler. On the other hand, when replacing the fixed quantity feeder for solid fuel, it is necessary to stop the solid fuel supply equipment and the operation of the circulating fluidized bed boiler itself. It is desirable to reduce downtime.

The present invention has been made in view of such a conventional situation, and a quantification of powder or granular material attached to the bottom of a silo, such as a limestone powder or a solid fuel supply facility provided in a circulating fluidized bed boiler. It is possible to easily and quickly attach / detach the feeder, thus avoiding the shutdown of the main equipment to which the powder or granular material such as the circulating fluidized bed boiler is supplied, or stopping the operation of the main equipment. In this case, the purpose is to provide a bogie with an elevating mechanism (also referred to as a lifter) used when replacing the metering feeder, which can shorten the downtime, and a method for attaching / detaching the metering feeder using the bogie. There is.

In order to achieve the above-mentioned object, the trolley having the elevating mechanism according to the present invention is a trolley for replacing the metering feeder attached to the bottom of the silo, and maintains the posture in which the metering feeder is attached to the silo. It is characterized by having a support portion provided with an elevating mechanism that supports the vehicle as it is.

Further, the quantitative feeder attachment / detachment method according to the present invention is a method of attaching / detaching the quantitative feeder located at the bottom of the silo using a carriage having a support portion provided with an elevating mechanism, and the elevating mechanism is lowered. A trolley is arranged below the silo, the elevating mechanism is raised below the silo, and the elevating mechanism is removed or attached while the quantitative feeder is supported by the support portion, and after the work is completed, the elevating mechanism is lifted. It is characterized in that the dolly is moved from below the silo by lowering it.

According to the present invention, it is possible to easily and quickly replace the quantitative feeder without using a large-scale device, and thereby, for example, a circulating fluidized bed boiler to which the powder or granular material cut out by the quantitative feeder is supplied. It is possible to avoid the shutdown of the main equipment, or to significantly reduce the downtime when the main equipment is shut down.

It is a schematic flow chart of a circulating fluidized bed boiler equipped with the supply equipment of solid fuel and desulfurizing agent which can suitably utilize the carriage provided with the elevating mechanism which concerns on this invention at the time of attachment and detachment work. It is a schematic flow chart of the supply equipment of solid fuel and desulfurizing agent of FIG. It is a schematic side view (a) and front view (b) of the table feeder included in each supply equipment of FIG. It is a side view (a) and the front view (b) of a specific example of a trolley provided with an elevating mechanism according to the present invention. It is a perspective view of the carriage provided with the elevating mechanism of FIG. It is a side view (a) and the front view (b) which show the state before the carriage provided with the elevating mechanism of FIG. 4 is arranged below the metering feeder. 4 is a side view (a) and a front view (b) showing a state in which the carriage provided with the elevating mechanism of FIG. 4 is arranged below the metering feeder and before the elevating mechanism is raised. 4 is a side view (a) and a front view (b) showing a state in which the carriage provided with the elevating mechanism of FIG. 4 raises the elevating mechanism and supports the quantitative feeder at the upper end thereof. 4 is a side view (a) and a front view (b) of a trolley provided with the elevating mechanism of FIG. 4 in a state where the elevating mechanism is lowered while supporting the fixed quantity feeder.

Hereinafter, a specific example of the carriage provided with the elevating mechanism of the present invention will be described in detail. First, with reference to FIG. 1, a circulating fluidized bed boiler equipped with a supply facility to which a carriage equipped with a lifting mechanism of a specific example of the present invention is suitably applied during attachment / detachment work will be described. The circulating fluidized bed boiler (hereinafter, also simply referred to as a boiler) shown in FIG. 1 is a vertical tubular combaster 1 having a tapered bottom and a flow that pops out with the combustion exhaust gas discharged from the upper part of the combustor 1. It is mainly composed of a cyclone 2 that recovers solids such as sand and a heat recovery unit 3 that recovers the heat of the combustion exhaust gas.

In the convertor 1, solid fuel such as coal is charged from the solid fuel supply facility 20 to the lower portion thereof, and a desulfurizing agent such as limestone powder for removing sulfur oxides in the combustion exhaust gas is charged from the desulfurizing agent supply facility 30. Will be done. Liquid sand such as silica sand is charged in the convertor 1 in advance, and the solid fuel and the desulfurizing agent are flowed by the air introduced from below the convertor 1 together with the fluid sand, whereby the solid fuel is burned. Progresses. The radiant heat transfer of the combustion exhaust gas generated by this combustion heats the boiler water flowing in the water pipe group (not shown) and partially evaporates it, whereby saturated steam is generated from the boiler drum 1a communicating with the water pipe group.

The combustion exhaust gas that has been heat-recovered by the above-mentioned radiant heat transfer leaves the combustor 1 as combustion exhaust gas and is introduced into the cyclone 2. Here, after solids such as fluidized sand are removed, heat is recovered by convection heat transfer. It is introduced into the heat recovery unit 3. The heat recovery unit 3 is provided with a super heater 3a that heats the saturated steam discharged from the boiler drum 1a by heat exchange with the combustion exhaust gas to generate superheated steam for private power generation. Further, the first economizer 3b that preheats the boiler water supplied from the boiler water tank 4 via the degassing device 5 by the heat exchange, and the second economizer 3c that preheats the air supplied from the blower 7 by the heat exchange. Is provided. The superheated steam generated by the super heater 3a is introduced into the turbine generator 6 and used for the rotation of the turbine, and then condensed and recovered in the boiler water tank 4.

The combustion exhaust gas that has been heat-recovered by the heat recovery unit 3 is introduced into the electrostatic precipitator 8 to remove dust, and then is released to the atmosphere from the chimney 9. The chimney 9 is provided with an SOx concentration meter 9a, and measures the SOx concentration of the combustion exhaust gas flowing in the chimney. The SOx concentration value measured by the SOx concentration meter 9a is input to the control means 10 such as DCS, and an operation is performed according to a predetermined algorithm here, and based on the calculation result, it is used for a desulfurizing agent such as limestone powder. The rotation speed of the motor M that drives the rotating portion of the fixed quantity feeder is controlled.

Next, the solid fuel supply facility 20 and the desulfurization agent supply facility 30 will be described with reference to FIG. 2 by taking as an example a case where the solid fuel is coal and the desulfurization agent is limestone powder. The solid fuel supply facility 20 that supplies granular coal to the convertor 1 of the circulating fluidized layer boiler described above includes a fuel hopper 21 that temporarily receives coal transported from a stockyard or the like by a belt conveyor or the like, and a fuel hopper 21. A fuel silo 22 that receives and stores coal discharged from the bottom, and a fuel quantitative feeder 23 such as a rotary valve or a table feeder that is provided at the bottom of the fuel silo 22 and performs quantitative cutting of the coal. The coal is mainly composed of the fuel air transportation piping system 24 for transporting the coal cut out from the fuel quantitative feeder 23 using compressed air as a transportation medium.

Similarly, the desulfurizing agent supply facility 30 for supplying limestone powder includes a desulfurizing agent hopper 31 that temporarily receives powdery limestone powder delivered in a package such as a flexible container bag, and a desulfurizing agent hopper 31. A silo 32 for a desulfurizing agent that receives and stores limestone powder discharged from the bottom of the silo 32, and desulfurization of a rotary valve, a table feeder, or the like provided at the bottom of the silo 32 for a desulfurizing agent to quantitatively cut out the limestone powder. It is mainly composed of a quantitative feeder 33 for an agent and an air transport piping system 34 for a desulfurizing agent that conveys the limestone powder cut out from the quantitative feeder 33 for a desulfurizing agent using compressed air as a transport medium.

In the above-mentioned quantitative feeder 23 for fuel and the quantitative feeder 33 for desulfurizing agent, the cutting amount is controlled by, for example, the rotation speed control by an inverter motor. Further, the above-mentioned air transportation piping systems 24 and 34 are all cut off from the air transportation piping systems 24 and 34 when the quantitative feeders 23 and 33, which will be described later, are replaced before and after the portions to which the quantitative feeders 23 and 33 are connected, respectively. The shutoff valves 24a, 24b and 25a, 25b are provided, respectively. Further, the solid fuel supply equipment 20 and the desulfurization agent supply equipment 30 are provided with a bypass piping system so that the circulation fluidized bed boiler can be continuously operated when the quantitative feeders 23 and 33 are replaced, respectively. Reserve supply facilities 25 and 35, which are simple hoppers, are provided, respectively.

Next, the schematic structure of the fuel quantitative feeder 23 and the desulfurization agent quantitative feeder 33 will be described by taking the case where the quantitative feeder is a table feeder as an example. Since the fuel quantitative feeder 23 and the desulfurizing agent quantitative feeder 33 have substantially the same structure, the desulfurizing agent quantitative feeder 33 will be described below.

As shown in FIG. 3, the quantitative feeder 33 for a desulfurizing agent rotates about a powder or granular material supply unit 41 including a cylindrical housing and a rotating portion that rotates inside the cylindrical housing, and an axis extending the rotating portion in the vertical direction. It is mainly composed of a drive unit 42 mainly composed of a motor and gears, has a high center of gravity due to its structure, and has a shape that easily falls when it is removed and placed on a table as it is. The powder or granular material supply unit 41 is located above the inlet 41a, which serves as a receiving port for limestone powder falling from the silo for desulfurization agent 32, and the limestone received into the cylindrical housing from the inlet 41a. The discharge nozzle 41b, which the powder passes through when the powder is quantitatively cut out toward the desulfurizing agent air transport piping system 34 by the rotation of the rotating portion, and the internal pressure of the cylindrical housing are applied to the inside of the desulfurizing agent silo 32. A pressure equalizing nozzle 41c is provided to which a pressure equalizing line for equalizing the pressure is connected.

By providing the pressure equalizing line as described above, a pressure difference does not occur between the inside of the cylindrical housing of the table feeder and the inside of the desulfurizing agent hopper 31, so that the silo 32 for the desulfurizing agent to the cylinder of the table feeder It is possible to suppress the problem that the limestone powder is difficult to be supplied to the shape housing, and conversely, the limestone powder flows back from the cylindrical housing toward the silo 32 for the desulfurizing agent and blows out in the silo.

Next, a specific example of the carriage provided with the elevating mechanism of the present invention will be described with reference to FIGS. 4 and 5. The carriage 50 provided with the elevating mechanism of one specific example of the present invention has a substantially rectangular flat plate-shaped base portion 51 having four wheels 51a on the lower surface side and a handle portion 51b on the upper surface side, and the base portion 51. It is located on the upper surface side of the base portion 51 and is composed of an elevating support portion 52 that supports the metering feeder 33. The structure of the support portion 52 is not particularly limited as long as it can support the quantitative feeder 33 while maintaining the posture of being attached to the desulfurizing agent silo 32 and move it up and down. An elevating table 53 having a substantially rectangular shape smaller than that of the base portion 51, a pantograph mechanism 54 for raising and lowering the elevating table 53 with respect to the base portion 51, and 1 provided on the upper surface side of the elevating table 53. It is preferably composed of a pair of rectangular gate-shaped structures 55.

The pair of structures 55 described above can support the surface of the quantitative feeder 33 opposite to the flange surface of the connecting flange with the desulfurizing agent silo 32 located at the upper end thereof. Is preferably provided so as to face the elevating table 53 in the width direction. Further, each structure 55 is preferably composed of a contact portion 55a extending in the horizontal direction and two leg portions 55b supporting both ends of the contact portion 55a from below.

The pair of structures 55 are separated from each other so that the contact portions 55a can support only both ends of the flange F of the quantitative feeder without interfering with the drive portion 42. The distance W is preferably about 150 to 450 mm, more preferably about 300 mm. Further, in the pair of structures 55, the height H of each structure 55 is 200 to so that the drive portion 42 does not interfere with the elevating table 53 when the quantitative feeder 33 is supported by the contact portions 55a. It is preferably about 600 mm, more preferably about 400 mm.

The pair of structures 55 may be reinforced by connecting the legs 55b facing each other in the width direction of the elevating table 53 with a reinforcing material such as a rod-shaped member extending in the horizontal direction or the diagonal direction. .. At that time, it is preferable that only the handle portion 51b side of the two leg portions 55b of each structure 55 is reinforced, and the side opposite to the handle portion 51b side is not reinforced. As a result, the carriage 50 can be moved directly under the metering feeder 33 without interfering with the drive unit 42 located below the metering feeder 33 even when the lifting table 53 is hardly lowered. Therefore, the replacement work can be completed in a shorter time. Further, since the reinforcing material is not present, the bolts and nuts connecting the quantitative feeder 33 and the desulfurizing agent silo 32, the discharge nozzle 41b, the pressure equalizing nozzle 41c, and the like can be easily removed and attached. Will be possible.

Next, a method of attaching / detaching the quantitative feeder using the carriage 50 provided with the above-mentioned elevating mechanism will be described with reference to FIGS. 6 to 9. First, a case where the quantitative feeder 33 is removed from the desulfurizing agent silo 32 will be described. When the quantitative feeder 33 is removed from the desulfurizing agent silo 32, the operations are performed in the order of the following first to fourth steps. That is, in the first step, as shown in FIG. 6, the trolley 50 is moved in the direction of the white arrow in a state where the pantograph mechanism 54 is folded and contracted, that is, in a state where the elevating table 53 is lowered, and the quantitative feeder 33 is used. Arrange so that a pair of structures 55 are directly below.

In the second step, as shown in FIG. 7, the pantograph mechanism 54 is extended in the direction of the white arrow to raise the elevating table 53. As a result, both contact portions 55a of the pair of structures 55 are brought into contact with the surface of the upper end of the metering feeder 33 on the side opposite to the flange surface of the flange F without interfering with the drive portion 42, and the flange is brought into contact with the flange. It becomes possible to support F. At that time, depending on the structure of the quantitative feeder 33, the bolts and nuts of the flange F for attaching to the desulfurizing agent silo 32 may interfere with the contact portion 55a, and the flange F may not be stably supported by the corresponding contact portion 55a. is there. In this case, it is preferable to remove some of the interfering bolts and nuts before raising the elevating table 53. Further, in order to improve workability, the bolts and nuts of the discharge nozzle 41b of the metering feeder 33 and the pressure equalizing nozzle 41c may be removed before raising the elevating table 53.

In the third step, as shown in FIG. 8, all the bolts and nuts of the flange F are removed while the quantitative feeder 33 is supported by the pair of structures 55. In the fourth step, the pantograph mechanism 54 is contracted in the direction indicated by the white arrow in FIG. 8 to lower the elevating table 53. Then, as shown by the white arrow in FIG. 9, the carriage 50 is moved from below the desulfurizing agent silo 32.

When the quantitative feeder 33 is attached to the desulfurizing agent silo 32, the operation is basically the reverse of the operation of removing the quantitative feeder 33 as shown in the following 5th to 8th steps. That is, in the fifth step, the trolley 50 in which the replacement quantitative feeder 33 is supported by the pair of structures 55 is attached to the quantitative feeder 33 of the desulfurizing agent silo 32 in the state where the elevating table 53 is lowered. Place it directly below the position.

In the sixth step, by extending the pantograph mechanism 54 and raising the elevating table 53, the flange F at the upper end of the quantitative feeder 33 is attached to the flange on the other side provided at the bottom of the desulfurizing agent silo 32. The flange surfaces are brought into contact with each other via a gasket. In the seventh step, both flanges are fastened with bolts and nuts. In the eighth step, the pantograph mechanism 54 is contracted to lower the elevating table 53.

In the seventh step, the bolts and nuts that are in a position where it is difficult to fasten because they interfere with both abutting portions 55a of the pair of structures 55 are fastened after lowering the elevating table 53 in the eighth step. May be good. Further, the bolts and nuts of the discharge nozzle 41b and the pressure equalizing nozzle 41c may be fastened in the seventh step or after the eighth step in consideration of workability and the like.

As described above, it is generally difficult to handle the quantitative feeder because it is structurally located at a high center of gravity or has a shape that easily falls when placed on a flat table. However, as described above, the present invention By using a trolley equipped with the elevating mechanism of the above, the attachment / detachment work can be performed in a state where the flange surface at the upper end of the metering feeder is stably supported while keeping the flange surface horizontal. Further, since the detachable quantitative feeder can be moved up and down in the vertical direction without tilting by simply raising and lowering the lifting mechanism, it is possible to easily perform the replacement work with a small number of workers.

[Example]
A hand lifter (HLF-S250B) manufactured by TRUSCO NAKAYAMA Co., Ltd. was prepared, and as shown in FIG. 4, a pair of rectangular gate-shaped structures produced by processing equilateral angle steel on the upper surface side of the lifting table 53. The body 55 was attached by welding to produce a trolley equipped with an elevating mechanism. At that time, the separation distance W for separating the pair of structures 55 in the width direction of the elevating table 53 was set to 300 mm, and the height H of the pair of structures 55 was set to 400 mm.

By using the trolley equipped with the elevating mechanism manufactured in this way, it is possible to replace the fixed quantity feeder replacement work, which used to take about 5 hours, in about 2 hours. Became. In addition, the chain block that suspends the metering feeder and its supporting legs are no longer required. As described above, by using the trolley provided with the elevating mechanism having the requirements of the present invention, it has become possible to easily and quickly replace the metering feeder.

1 Combustor 1a Boiler drum 2 Cyclone 3 Heat recovery unit 3a Super heater 3b 1st economizer 3c 2nd economizer 4 Boiler water tank 5 Degassing device 6 Turbine generator 7 Blower 8 Electrodust collector 9 Chimney 9a SOx densitometer 10 Control means 20 Solid fuel Supply equipment 21 Fuel hopper 22 Fuel silo 23 Fuel quantitative feeder 24 Fuel air transport piping system 24a, 24b, 25a, 25b Shutoff valve 25 Fuel reserve supply equipment 30 Desulfurizing agent supply equipment 31 Desulfurizing agent hopper 32 Desulfurizing agent Silo 33 Fixed-quantity feeder for desulfurizing agent 34 Air transport piping system for desulfurizing agent 35 Preliminary supply equipment for desulfurizing agent 41 Powder and granule supply unit 41a Input port 41b Discharge nozzle 41c Pressure equalizing nozzle 42 Drive unit 50 Cart 51 Base 51a Wheel 51b Handle 52 Support 53 Lifting table 54 Pantograph mechanism 55 Structure 55a Contact 55b Leg

Claims (5)

It is a trolley for replacing the metering feeder attached to the bottom of the silo, and has a support portion provided with an elevating mechanism for supporting the metering feeder while maintaining the posture of being attached to the silo. A dolly characterized by that. The carriage according to claim 1, wherein the silo constitutes a supply facility for charging a solid fuel or a desulfurizing agent into a combustor of a circulating fluidized bed boiler. A method of attaching and detaching a quantitative feeder located at the bottom of the silo using the trolley according to claim 1, wherein the trolley is arranged below the silo with the elevating mechanism lowered, and below the silo. The elevating mechanism is raised and the quantitative feeder is supported by the support portion while being removed or attached. After the work is completed, the elevating mechanism is lowered to move the trolley from below the silo. A characteristic method for attaching and detaching a quantitative feeder. When removing the metering feeder from the silo, the first step of arranging the carriage provided with the lifting mechanism below the metering feeder with the lifting mechanism lowered, and raising the lifting mechanism at the support portion. It is characterized by including a second step of supporting the flange at the upper end of the metering feeder, a third step of removing the bolts and nuts of the flange while the flange is being supported, and a fourth step of lowering the elevating mechanism. The method for attaching / detaching the quantitative feeder according to claim 3. When the metering feeder is attached to the silo, a carriage provided with the lifting mechanism in a state where the replacement metering feeder is supported by the support portion is arranged below the silo with the lifting mechanism lowered. The fifth step, the sixth step of raising the elevating mechanism to bring the flange located at the upper end of the quantitative feeder into contact with the flange on the other side, the seventh step of attaching the bolts and nuts of the flange, and the said. The method for attaching / detaching a quantitative feeder according to claim 3, further comprising an eighth step of lowering the elevating mechanism.

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