Boiler system and boiler operation method

Abstract

To provide a boiler system that eliminates the need for special handing work when using a solution fuel which solidifies at room temperature (waste lubricant oil, waste edible oil and by-product oil) as fuel.SOLUTION: A boiler system comprises: a boiler 11 which operates with a solution fuel solidifying at room temperature and / or a liquid fuel (A fuel oil, B heavy oil and regeneration oil) to generate steam; a solution fuel tank 1 which reserves the solution fuel; a starting / stopping fuel tank 2 which reserves the liquid fuel; a first warming device 3 which warms the fuel with the steam of the boiler 11; circulation piping 30 which has inflow piping for letting the fuel flow in the boiler and outflow piping for letting the fuel flow out of the boiler; a second warming device 5 which warms the fuel supplied to the boiler through the circulation piping 30 with the steam of the boiler; and warming means which warms transport piping and the circulation piping with the steam of the boiler.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a boiler system that generates consumed steam and a method for operating a boiler, and more particularly to a boiler system configuration and boiler operating method for preventing the solution fuel from solidifying in the piping that supplies fuel to the boiler. [Background technology]

[0002] In Japan, a country with few energy resources, the use of solution fuels (by-product oils) as fuels has been researched and put to practical use. In recent years, due to the demand for reducing CO2 emissions and the rise in the unit price of imported fuels, it is expected that solution fuels (by-product oils) will be used as fuels from the perspective of effective resource utilization. There are various types of solution fuels that can be used as fuels, such as waste lubricating oil, waste cooking oil, and waste chemical oil, and some of them solidify at room temperature (below 40 degrees). 2. Description of the Related Art A boiler (multi-tube once-through boiler) capable of using waste oil as combustion gas for generating consumed steam is disclosed in, for example, Patent Document 1 proposed by the present inventor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2019-190781 Summary of the Invention [Problem to be solved by the invention]

[0004] When using liquid fuel that solidifies or has high viscosity at room temperature as boiler fuel, it is necessary to heat the fuel to ensure that it is liquefied when the boiler is started up, and to remove the fuel when the boiler is shut down to prevent it from solidifying in the piping, which poses the problem of complicated handling operations.

[0005] The present invention has been proposed in consideration of the above-mentioned situation, and aims to provide a boiler system and a boiler operating method that eliminates the need for special handling procedures when using liquid fuel as fuel, by providing a boiler system equipped with a structure that uses heat from an operating boiler to prevent liquid fuel such as waste oil from solidifying in the piping. [Means for solving the problem]

[0006] In order to achieve the above object, the boiler system according to claim 1 of the present invention comprises: Through the switching valve (19) By supplying fuel A boiler (11) that is in operation and generates steam; As the fuel A solution fuel tank (1) for storing a solution fuel that solidifies at room temperature; The fuel is liquid A start-up / shutdown fuel tank (2) for storing fuel; Through the transport pipe (31) hand a first heating device (3) that heats the supplied fuel with steam from the boiler (11); a fuel pump (6) for transporting the fuel to the first heating device (3); an inlet pipe for introducing the fuel into the boiler (11), and an outlet pipe for discharging the fuel from the boiler (11); The inlet pipe and the outlet pipe are connected to each other at their respective ends, and the fuel is supplied from the first heating device (3) through a ring-shaped pipe section (30a). The fuel can be circulated in the pipe section (30a) by installing a circulation pump (9). A circulation pipe (30); From the transport pipe (31) a second heating device (5) that heats the fuel supplied to the boiler (11) through the circulation piping (30) with steam from the boiler (11); an oil pump (8) for transporting the fuel to a second heating device (5); a heating means for heating the transport pipe (31) and the circulation pipe (30) with steam from the boiler (11). picture, By operating the switching valve (19), the fuel in the transport pipe (31) and the circulation pipe (30) can be replaced between the solution fuel (lubricating waste oil, edible waste oil, chemical waste oil, by-product oil) and the liquid fuel (heavy oil A, heavy oil B, recycled oil). thing It is characterized by:

[0007] Claim 2 provides the boiler system of claim 1, A line heater (17) equipped with an electric heating wire is installed in the annular piping portion (30a). It is characterized by the following.

[0008] Claim 3 is the boiler system of claim 1 or claim 2, The boiler (11) is provided with a waste heat recovery device (12) that heats water by utilizing exhaust gas combusted in the boiler (11), and a water supply pump (10) is connected to the upstream portion of the water supply to the waste heat recovery device (12).

[0009] Claim 4 provides a boiler system according to any one of claims 1 to 3, A plurality of boilers (11) are connected to the first heating device (3) via an oil pump (8), a second heating device (5) and a circulation pipe (30), respectively.

[0010] Claim 5 provides the boiler system of claim 4, When a plurality of boilers (11) are connected to the first heating device (3), steam is supplied to the first heating device (3) and to the second heating devices (5) connected to each of the boilers (11) through separate lines.

[0011] The boiler operating method according to claim 6 comprises: Fuel supply Being 1. A method of operating a boiler to generate steam, comprising the steps of: A switching valve (19) is provided for switching between a solution fuel that solidifies at room temperature and a liquid fuel as the fuel, The system is characterized by including a fuel heating device (a first heating device 3 and a second heating device 5) for heating the fuel to be supplied to the boiler (11), and by including the following steps: When the boiler (11) is started up, the switching valve (19) liquid Procedures for supplying fuel (Fuel Oil A, Heavy Oil B, Recycled Oil) and running the plant. After the fuel heating device starts to operate due to the operation of the boiler (11) and the fuel is sufficiently heated, the switching valve (19) is switched to supply the solution fuel (lubricating waste oil, cooking waste oil, chemical waste oil, by-product oil). , heating in the annular piping portion (30a) Procedures for circulating and operating. A procedure for replacing solution fuels (lubricating waste oil, edible waste oil, chemical waste oil, by-product oil) in the piping (circulation piping 30 and transport piping 31) with liquid fuels (heavy oil A, heavy oil B, recycled oil) by switching the switching valve (19) before stopping the boiler (11). and a procedure for shutting down the boiler (11) once the replacement is completed. Effect of the Invention

[0012] According to the present invention, when a liquid fuel (waste lubricating oil, waste edible oil, chemical waste oil, by-product oil) that is solid or has high viscosity at room temperature is used as fuel for the boiler (11), the fuel can be heated stably and efficiently by providing a fuel heating device (first heating device 3 and second heating device 5) that uses steam from the boiler (11). In addition, by providing a mechanism for replacing the solution fuel (lubricating waste oil, edible waste oil, chemical waste oil, by-product oil) in the piping (circulation piping 30 and transport piping 31) with liquid fuel (heavy oil A, heavy oil B, recycled oil) before the boiler is stopped, it is possible to prevent the solution fuel (lubricating waste oil, edible waste oil, chemical waste oil, by-product oil) from being left in the piping and solidifying. [Brief description of the drawings]

[0013] [Figure 1] 1 is a line explanatory diagram showing an entire boiler system according to the present invention. FIG. [Diagram 2] 1 is a side explanatory diagram showing a configuration of a boiler system according to the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An embodiment of a boiler system according to the present invention will be described with reference to the drawings. Figures 1 and 2 show the entire boiler system, which is composed of a solution fuel tank 1 and a start / stop fuel tank 2 for storing boiler fuel, a first heating device 3 and a second heating device 5 as fuel heating devices for heating the boiler fuel, a boiler 11 equipped with a burner 11a for generating consumed steam from supplied water, and a waste heat recovery device (economizer) 12 that uses boiler waste heat to heat water and supply it to the boiler 11. The boiler system according to the present invention is characterized by its configuration that allows for the stable and efficient use of liquid fuels (waste lubricating oil, waste edible oil, chemical waste oil, by-product oil) that are solid or have high viscosity at room temperature as boiler fuel. As a boiler that can use waste oil as fuel, the structure described in the above-mentioned Patent Document 1 (JP 2019-190781 A) can be used.

[0015] A circulation pipe 30 that supplies boiler fuel to the boiler 11 and a feed water pump 10 that supplies water to the boiler 11 are connected to the boiler 11. Boiler fuel is sent to the circulation pipe 30 from a second heating device 5 that heats and stores the boiler fuel using an oil feed pump 8. These devices are installed in the boiler room, and one or more boiler rooms are each connected to facilities outside the boiler room (facility within the factory). Therefore, the second heating device 5 is a dedicated tank for one boiler 11. Water mixed with liquid from a chemical injection device 20 connected to a water supply pump 10 is supplied to the boiler 11, and steam is generated by burning boiler fuel in a burner 11a, and the steam is sent out from a main steam pipe 40 (Figure 2). A gas cylinder 21 (Fig. 1) for ignition, which serves as the burner fuel supply source, is connected to the burner 11a. Boiler burners usually use a method called "direct ignition," in which a spark is generated with an electrode rod and fuel is sprayed onto it to ignite the burner. The above-mentioned boiler system uses fuel that solidifies at room temperature, so the flash point (the temperature at which the fuel begins to catch fire) is higher than that of ordinary fuel, and there is a possibility that the fuel may not ignite with a spark. Therefore, to increase the reliability of ignition, a method called "gas pilot ignition" is used, in which a spark is generated with an electrode rod, a pilot burner (using gas) is ignited, and fuel is sprayed onto it to ignite the burner.

[0016] The factory facilities include a first heating device 3 having a regular fuel tank for storing solution fuel (lubricating waste oil, edible waste oil, chemical waste oil, by-product oil) that will be used as boiler fuel from a solution fuel tank 1 and a start-and-shutdown fuel tank 2, a service tank 4 for storing liquid fuel (heavy oil A, heavy oil B, recycled oil) that will be used as boiler fuel, and a water supply tank 14 for storing water from a water softener 13 and supplying it to a water supply pump 10. The first heating device 3 is connected to the solution fuel tank 1 via a switching valve 19, a fuel delivery pump 6, and an autofilter 15 installed in a transport pipe 31, and stores and heats the solution fuel for use in the boiler 11. The service tank 4 is connected to the start / stop fuel tank 2 via the start / stop fuel delivery pump 7, and stores liquid fuel (A heavy oil, B heavy oil, recycled oil) for use in the boiler 11. The liquid fuel from the service tank 4 is supplied to the first heating device 3 by switching the switching valve 19. The first heating device 3 and the service tank 4 are installed outside the boiler room and serve as tanks for supplying water to other boilers, other devices, etc.

[0017] The circulation pipe 30 has an inlet pipe for introducing fuel into the boiler 11 and an outlet pipe for discharging fuel from the boiler 11, and is equipped with a pipe section 30a made of a metal pipe with a circulation pump interposed therebetween, and a flexible section 30b for allowing the pipe to be bent. The pipe section 30a is equipped with a multiple strainer 16 in which strainers for removing solids from the solution fuel are arranged in parallel. Normally, only one of the multiple strainers 16 is used, and by switching to the other one during maintenance or when the strainer becomes clogged, maintenance can be performed without stopping the solution fuel. Due to the characteristics of the solution fuel, it is preferable to use a multiple strainer because it is prone to clogging.

[0018] As shown in FIG. 2, the solution fuel tank 1, the first heating device 3 and the second heating device 5 are configured to heat the boiler fuel stored in the solution fuel tank 1, the first heating device 3 and the second heating device 5 by branching off a heating steam pipe 41 from a main steam pipe 40 for supply steam discharged from the boiler 11, and guiding the heating steam pipe 41a to the heating tank of the second heating device 5, the heating steam pipe 41b to the regular fuel tank of the first heating device 3 and the heating steam pipe 41c to the solution fuel tank 1 into heating coils respectively installed therein.

[0019] The circulation pipe 30 and the transport pipe 31 are also provided with heating means for heating them with steam from the boiler 11. That is, the heating means is configured to heat the surfaces of the pipes by guiding steam through the steam header 18 to heating coils installed in a coil shape around the outer surfaces of the circulation pipe (piping section 30a) and the transport pipe 31 (solid line hatched areas in FIG. 1). The steam header 18 temporarily collects the steam coming out of the boiler, separates it into water and steam to prevent the dryness of the steam from decreasing, and distributes it to each pipe beyond the valve.

[0020] Steam is supplied to the first heating device 3 and the transport piping 31, and to the second heating device 5 and the circulation piping 30 via a steam header 18, so that steam can be supplied to the regular fuel tank of the first heating device 3 and the heating tank of the second heating device 5 via separate lines (Figure 1).

[0021] A line heater 17 is installed in the circulation pipe (piping section 30a), and an electric heating wire is arranged in the pipe so that the temperature is increased to a set temperature by a temperature sensor. Moreover, a heater band (electrically operated) is attached to the flexible portion 30b of the circulation pipe for heating (the portion indicated by the dotted and diagonal lines in FIG. 1).

[0022] In the above-described boiler system, an example has been described in which one boiler 11 is connected to the first heating device 3 via an oil pump 8, a second heating device 5, and a circulation piping 30, but multiple boilers may be connected to the first heating device 3, each via an oil pump, a second heating device, and a circulation piping. When multiple boilers are installed for the first heating device 3, the steam header 18 temporarily collects steam from the multiple boilers and distributes it to each pipe beyond the valve. In this case, steam is supplied to the first heating device and the second heating device through separate lines. Therefore, when multiple boilers are installed, the piping for the boiler that is stopped does not need to be heated because it is filled with liquid fuel such as heavy oil A. By being able to heat each boiler in accordance with its startup, it is possible to make effective use of thermal energy.

[0023] A waste heat recovery device (economizer) 12 is connected to the exhaust side of the boiler 11. The waste heat recovery device 12 is a device that uses exhaust gas burned in the boiler 11 to heat water and supply it to the boiler 11, and is configured such that a feed water pump 10 that supplies water to the boiler 11 is connected to the upstream portion of the water supply to the waste heat recovery device 12. The feed water pump 10 is installed in the upstream portion of the waste heat recovery device 12 for the following reasons.

[0024] Because the water supply pump 10 has a suction force at the pump inlet, some of the water turns to gas at temperatures in the latter half of 90°C, causing cavitation, which can damage the pump or cause it to run idly and prevent it from pumping out water. For this reason, even with conventional pumps that are designed for high temperatures, the maximum temperature of the water supply was limited to 95°C. Also, when the temperature of the water in the pipe exceeds 100°C, some of the water in the pipe turns to gas, and if this gas enters the pump, the pump cannot pump out the gas, causing it to be unable to supply water.

[0025] In the above-described boiler system, a pump of a normally used structure is used as the water supply pump 10, but by installing it on the inlet side of the waste heat recovery device 12, water can be supplied to the waste heat recovery device 12 even if the water temperature in this area is around 90 to 95°C. In this embodiment, the temperature of the water supplied via the water supply pump 10 can be set to a room temperature to about 90°C, and the temperature of the water discharged from the waste heat recovery device 12 can be set to a value exceeding 150°C.

[0026] In addition, since the liquid fuel (waste lubricating oil, waste edible oil, chemical waste oil, by-product oil) used as fuel for the boiler may contain a large amount of ash, a dust collector 50 is installed on the exhaust side of the waste heat recovery device 12 so that the dust from the exhaust gas from the waste heat recovery device 12 is collected by the dust collector 50 and released.

[0027] Next, a method for operating the above-mentioned boiler system will be described. The boiler system of the present invention uses two types of fuel: fuel that is liquid at room temperature (heavy oil A, heavy oil B, recycled oil) that is used during startup and shutdown, and solution fuel which is waste oil (waste lubricating oil, waste edible oil, chemical waste oil, by-product oil).

[0028] At the start-up of operation, liquid fuel (heavy oil A, heavy oil B, recycled oil) is supplied from the service tank 4 to the boiler 11 via the switching valve 19 and burned, heating the solution fuel tank 1, the regular fuel tank of the first heating device 3, and the heating tank of the second heating device 5. At the time of starting up the operation, the solution fuel tank 1 to the switching valve 19 is filled with solution fuel that solidifies at room temperature, and the tanks and piping beyond that are filled with liquid fuel (heavy oil A, etc.), but even if solidified fuel remains in the solution fuel tank 1, it will be melted by heating. In addition, the circulation piping 30 and the transport piping 31 filled with liquid fuel (heavy oil A, heavy oil B, recycled oil) are also heated. After the temperature of the solution fuel (lubricating waste oil, cooking waste oil, chemical waste oil, by-product oil) reaches a melting point (a state where it becomes liquid and can flow) due to heating by the fuel heating devices (first heating device 3 and second heating device 5), the fuel is switched to the solution fuel (lubricating waste oil, cooking waste oil, chemical waste oil, by-product oil) by the switching valve 19. Since the circulation pipe 30 and transport pipe 31 are heated, the solution fuel does not cool down and solidify in the pipes when switching.

[0029] When shutting down, the solution fuels (lubricating waste oil, edible waste oil, chemical waste oil, by-product oil) in the circulation pipes 30 and transport pipes 31 and in the tanks are replaced with liquid fuels (heavy oil A, heavy oil B, recycled oil), and once the replacement is complete, the boiler operation is stopped. Since the fuel in the circulation pipe 30 and the transport pipe 31 has been replaced with liquid fuel from the solution fuel, the fuel does not solidify in the pipes at room temperature after the operation is stopped.

[0030] That is, when the boiler system is started up and running, the liquid fuel (heavy oil A, heavy oil B, recycled oil) stored in the service tank 4 is sent through the switching valve 19 to the first heating device 3 and the second heating device 5 as boiler fuel, steam is generated in the boiler 11, and the steam is guided into the heating coil to heat the solution fuel tank 1, the regular tank of the first heating device 3, the heated fuel tank of the second heating device 5, the circulation piping 30, and the transport piping 31. When the liquid fuel (heavy oil A, heavy oil B, recycled oil) is sufficiently heated, the switching valve 19 is switched and the boiler 11 is operated using the liquid fuel (waste lubricating oil, waste cooking oil, chemical waste oil, by-product oil).

[0031] When the boiler system is stopped, the switching valve 19 switches to liquid fuel for start-up and shutdown (heavy oil A, heavy oil B, recycled oil), and the solution fuel (lubricating oil waste, cooking oil waste, chemical waste oil, by-product oil) in the first heating device 3 and second heating device 5, circulation piping 30 and transport piping 31 is replaced with liquid fuel for start-up and shutdown (heavy oil A, heavy oil B, recycled oil) before the system is shut down.

[0032] When there are multiple boilers for the first heating device 3, the same procedure as above is carried out for each boiler. In addition, if there are multiple boilers already in operation, when starting up an additional boiler, there is a possibility that the solution fuel will be supplied and solidify before the circulation piping 30 and second heating device 5 for that boiler are sufficiently heated, so it is possible to heat the circulation piping 30 and second heating device 5 in advance by opening the valve on the heating line.

[0033] According to the boiler system described above, when the boiler 11 is started up, the heating device (first heating device 3 and second heating device 5) uses steam from the boiler to stably and efficiently heat liquid fuels (waste lubricating oil, waste edible oil, chemical waste oil, by-product oil) that are solid or have high viscosity at room temperature. When the boiler 11 is started up, it operates using liquid fuel (heavy oil A, heavy oil B, recycled oil), and when the boiler 11 is stopped, the solution fuel (lubricating waste oil, edible waste oil, chemical waste oil, by-product oil) in the piping (circulation piping 30 and transport piping 31) is replaced with liquid fuel (heavy oil A, heavy oil B, recycled oil), thereby preventing the solution fuel from being left in the piping and solidifying.

[0034] As a result, manual heating and fuel replacement work is no longer necessary, which reduces the complicated work involved in using solution fuels (waste lubricating oil, waste cooking oil, chemical waste oil, by-product oil) as boiler fuel. In addition, by using solution fuels (waste lubricating oil, waste edible oil, chemical waste oil, by-product oil), it is possible to achieve zero CO2 emissions in terms of calculated resource energy, thereby reducing CO2 emissions and fuel costs. [Explanation of symbols]

[0035] 1...Solution fuel tank 2. Start / stop fuel tank 3…First heating device 4. Service tank 5…Second heating device 6…Fuel pump 7…Start / stop fuel pump 8…Oil pump 9…Circulation pump 10…Water supply pump 11…Boiler 11a…Burner 12...Waste heat recovery device 13…Water softener 14…Water tank 15…Auto Filter 16…Double strainer 17...Line heater 18…Steam header 19...Switch valve 20...Medicine feeding device 21...Gas cylinder 30…Circulation piping 31...Transportation piping 40…Main steam pipe 50…Dust collector

Claims

1. A boiler that generates steam by supplying fuel through a switching valve; a solution fuel tank for storing a solution fuel that solidifies at room temperature as the fuel; a start / stop fuel tank for storing liquid fuel as the fuel; a first heating device that heats the fuel supplied through a transport pipe with steam from the boiler; a fuel pump that transports the fuel to a first heating device; an inlet pipe for introducing the fuel into the boiler, an outlet pipe for discharging the fuel from the boiler, and a circulation pipe having an annular piping section to which each end of the inlet pipe and the outlet pipe are connected and to which the fuel is supplied from the first heating device, the circulation pipe enabling the fuel to be circulated in the piping section by the installation of a circulation pump; a second heating device that heats the fuel supplied from the transport pipe to the boiler through the circulation pipe with steam from the boiler; an oil pump that transports the fuel to a second heating device; a heating means for heating the transport pipe and the circulation pipe with steam from the boiler; Equipped with The boiler system is configured so that the fuel in the transport pipe and the circulation pipe can be replaced between the solution fuel and the liquid fuel by operating the switching valve.

2. A boiler system as described in claim 1, in which a line heater equipped with an electric heating wire is installed in the annular piping section.

3. 3. A boiler system as claimed in claim 1 or 2, further comprising a waste heat recovery device which uses exhaust gas combusted in the boiler to heat water, and a water supply pump connected to a front stage of the water supply to the waste heat recovery device.

4. 4. The boiler system according to claim 1, wherein a plurality of boilers are connected to the first heating device via an oil pump, a second heating device, and a circulation pipe, respectively.

5. The boiler system according to claim 4, wherein when a plurality of boilers are connected to the first heating device, steam is supplied to the first heating device and the second heating device connected to each of the boilers through separate lines.

6. A method for operating a boiler which is supplied with fuel and generates steam, comprising the steps of: A switching valve is provided for switching between a solution fuel that solidifies at room temperature and a liquid fuel as the fuel, and a fuel heating device is provided for heating the fuel to be supplied to the boiler, supplying liquid fuel through the switching valve to operate the boiler at the time of starting up the boiler; a step of switching the switching valve to supply the solution fuel after the fuel heating device starts to operate by the operation of the boiler and the solution fuel is sufficiently heated, and then circulating and heating the solution fuel in a circular piping section to operate the solution fuel; before the boiler is stopped, the solution fuel in the piping is replaced with liquid fuel by switching the switching valve; a procedure for shutting down the boiler upon completion of said replacement; A method for operating a boiler comprising the steps of:

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