JP6537490B2 - Heat exchanger - Google Patents

Description

  In the present invention, a heat exchange pipe made of steel material for circulating a medium liquid is provided in a combustion furnace, and the combustion exhaust gas obtained by burning biomass fuel containing chlorine in the combustion furnace is brought into contact with the heat exchange pipe. The present invention relates to a heat exchanger for heating a medium liquid.

  In bamboo forests where large amounts of bamboo are grown and grown rapidly, and bamboo forests are left standing, bamboo spreads around, and forests such as adjacent cedars and bushes are eroded, causing problems such as destruction of their ecosystems. .

  For this reason, in recent years there have been more cases in which local governments etc. respond to harvesting of neglected bamboo groves, but harvested bamboo is an industrial waste, so disposal is expensive, which is an expense aspect. It is a heavy burden on

  Therefore, attempts have been made to use harvested bamboo as a biomass fuel. Patent Document 1 proposes utilizing bamboo resources by supplying bamboo chips to a boiler for a thermal power generator as fuel for power generation. Although this patent document 1 does not describe the details of the boiler, the boiler for thermal power generation has a heat transfer portion serving as a heat exchange pipe, and is heated by exhaust heat generated by burning the heat exchange pipe. Then, the medium in the heat exchange pipe is heated.

  By the way, bamboo contains a large amount of chlorine component, and burning bamboo produces chlorine gas. If bamboo is used as the fuel for the boiler, the heat exchange pipe will be exposed to the generated chlorine gas for a long time.

  Steel pipes are used for heat exchange pipes, and there is a problem that the pipes are corroded by being exposed to chlorine gas for a long time.

  Therefore, Patent Document 2 proposes using bamboo as a fuel by modifying bamboo and removing chlorine and potassium from bamboo. In Patent Document 2, bamboo is atomized to a particle diameter of 6 mm or less, and the atomized bamboo is immersed in water under normal pressure to elute chlorine and potassium, thereby removing chlorine and potassium from bamboo. Then, the bamboo soaked in water at normal pressure is dehydrated, and the dehydrated bamboo is used as a fuel.

  In the thing of the above-mentioned patent documents 2, by reforming chlorine from bamboo by reforming bamboo, generation | occurrence | production of chlorine gas can be prevented when using as a fuel. However, in order to reform bamboo, a process of soaking in water and a process of dehydrating bamboo are required, and the number of working processes to be used as fuel increases, causing problems such as an increase in cost.

JP, 2011-223971, A JP, 2016-125030, A

  An object of the present invention is to provide a heat exchanger capable of using bamboo as a fuel as it is without increasing the cost and preventing corrosion of the heat exchange pipe.

In the heat exchanger according to the present invention, in order to solve the problems as described above, a heat exchange pipe made of a steel material for circulating a medium liquid is provided in a combustion furnace, and biomass fuel containing chlorine is provided in the combustion furnace. And a heat exchanger for heating the medium liquid by bringing the burned flue gas into contact with the heat exchange pipe, and detecting the temperature of the medium liquid on the side flowing out from the heat exchanger; Temperature control means for adjusting the temperature of the medium liquid of the heat exchange pipe according to the detection output of the outflow side temperature detection means, provided on the side flowing into the heat exchanger; The temperature of the medium liquid flowing out of the heat exchanger is controlled to be 250 ° C. or more and 310 ° C. or less so that the temperature of the medium liquid in the heat exchanger becomes the dew point of hydrochloric acid or more and 400 ° C. or less .

  Further, in the above heat exchanger, the temperature adjusting means may include an inflow side temperature detecting means for detecting the temperature of the medium fluid flowing into the heat exchanger, and a flow rate of the medium fluid flowing into the heat exchanger. The flow rate control means may control the flow rate of the medium fluid flowing into the heat exchanger according to the outputs of the outflow side temperature detection means and the inflow side temperature detection means. .

  In addition, a bamboo material may be used as the biomass fuel.

  The present invention controls the temperature of the medium liquid in the heat exchanger to the dew point of hydrochloric acid or more and 400 ° C. or less, thereby generating heat exchange piping made of steel material even when chlorine gas is generated using biomass fuel containing chlorine. It can prevent corrosion. Even if a bamboo material is used as a biomass fuel, it can be used as a fuel without reforming, and the fuel can be inexpensive.

FIG. 1 is a schematic view illustrating an embodiment of the present invention. It is a figure which shows the relationship of the corrosion temperature and pipe wall temperature of piping for heat exchange when the fuel containing a chlorine component and a sulfur component is burned by a boiler.

  Hereinafter, a combustion apparatus according to an embodiment of the present invention will be specifically described based on the attached drawings. In addition, the combustion apparatus which concerns on this invention is not limited to what was shown to the following embodiment, In the range which does not change the summary of invention, it can change suitably and can implement.

  As shown in FIG. 1, the heat exchanger 1 according to the embodiment of the present invention has a heat exchange pipe 3 made of a steel material provided in a combustion furnace 10. The heat exchange pipe 3 is made of carbon steel pipe (STPG) for pressure pipe.

  The bottom of the combustion furnace 10 is provided with a grate 11 for retaining the bamboo chip 2 which is a biomass fuel containing chlorine and allowing incineration ash to fall while aerating. Air sent from a fan (not shown) or the like is supplied from the intake port 14 into the combustion furnace 10 through the plurality of holes 11 a of the grate 11.

  The combustion furnace 10 is provided with an inlet 12 a for supplying the bamboo chip 2, and the inlet 12 a is closed by the lid 12 except for supplying the bamboo chip 2.

  The bamboo chip 2 held on the grate 11 is ignited using an ignition device (not shown) to burn the bamboo chip 2. The incineration ash produced by combustion is dropped from the hole 11a.

  A heat exchange pipe 3 is provided in the upper part of the combustion furnace 10, and the combustion exhaust gas obtained by burning the bamboo chip 2 contacts the heat exchange pipe 3. A medium oil is sealed in the heat exchange pipe 3 as a medium liquid. This medium oil is heated by the combustion exhaust gas through the heat exchange pipe 3. The heated heat medium oil flows out to the heat exchange pipe 3 extending to the outside of the combustion furnace 10, and the medium oil whose temperature is lowered flows into the combustion furnace 10 through the external heat exchange pipe 3 . Thus, the medium oil is circulated in the heat exchange pipe 3 and thermally transported.

  An exhaust pipe 13 is provided above the heat exchange pipe 3, and the exhaust gas is exhausted from the exhaust pipe 13.

  An outflow side temperature detection device 31 is provided in the heat exchange pipe 3 extending to the outside of the combustion furnace 10, and detects the temperature of the medium oil flowing out. A temperature control device 32 for adjusting the temperature of the medium oil in the heat exchange pipe 3 in the heat exchanger 1 is provided in the heat exchange pipe 3 that allows the medium oil to flow into the combustion furnace 10.

  In this embodiment, the temperature control device 32 adjusts the flow rate of the medium oil flowing into the heat exchange pipe 3 in the combustion furnace 10 and the inflow side temperature detection device 32a that detects the temperature of the medium oil flowing in. And a flow control device 32b. The flow rate adjusting device 32 b is constituted by a valve, and adjusts the amount of medium oil flowing in by adjusting the opening degree of the valve.

  The temperature control device 32 adjusts the flow rate of the medium oil according to the output of the outflow side temperature detection device 31. In this embodiment, the output of the outflow side temperature detection device 31 and the output of the inflow side temperature detection device 32a Thus, according to the difference between the temperature of the medium oil being discharged and the temperature of the medium oil being input, the flow control device 32b is controlled to adjust the flow rate of the medium oil being input, and the temperature of the medium oil being Control to reach a predetermined temperature.

  When the output of the outflow side temperature detection device 31 is lower than a predetermined temperature and the difference between the output of the outflow side temperature detection device 31 and the output of the inflow side temperature detection device 32a is large, the amount of medium oil flowing in decreases. The flow rate adjusting device 32b adjusts the flow rate of the medium oil. In addition, when the output of the outflow side temperature detection device 31 is higher than or near the predetermined temperature, the difference between the output of the outflow side temperature detection device 31 and the output of the inflow side temperature detection device 32a is small. The flow control device 32b adjusts the flow rate of the medium oil so as to increase the amount of medium oil to be collected. Thus, the temperature control device 32 adjusts the temperature of the medium oil in the heat exchange pipe 3 of the heat exchanger 1 to a predetermined temperature.

  Biomass fuels include those containing chlorine, such as bamboo, and materials derived from animals that contain sulfur. The relationship between the corrosion temperature of the heat exchange pipe and the tube wall temperature when the fuel containing the chlorine component and the sulfur component is burned in the boiler is shown in FIG. Here, the heat exchange pipe is a carbon steel pipe (STPG) for pressure pipe.

  As shown in FIG. 2, at low temperatures up to the dew point of hydrochloric acid and sulfuric acid dew point, the corrosion rate increases as the tube wall temperature rises due to corrosion by hydrochloric acid and sulfuric acid generated by chlorine gas and sulfur disulfide gas generated by combustion. . When the dew point temperature is exceeded, the corrosion becomes corrosion due to the formation of iron chloride or alkali iron sulfate, and the corrosion hardly progresses until the tube wall temperature reaches 320 ° C. When the tube wall temperature exceeds 320 ° C., the corrosion rate increases, and when the tube wall temperature exceeds 500 ° C., corrosion occurs due to decomposition of iron chloride or alkali iron sulfate, and the corrosion temperature rapidly increases.

  It can be seen from FIG. 2 that when the tube wall temperature is 400 ° C. or less, the corrosion of the tube wall does not progress so much. Therefore, in the present invention, the temperature control device 32 is controlled so that the temperature of the pipe wall of the heat exchange pipe 3 is equal to or higher than the hydrochloric acid dew point and equal to or lower than 400.degree. The temperature of the medium oil in the heat exchange pipe 3 of the heat exchanger 1 is controlled to be controlled to the dew point of hydrochloric acid or more and 400 ° C. or less.

  Then, it can be seen that corrosion does not proceed when the dew point temperature is exceeded in view of corrosion, but if the temperature is too low, the efficiency of the heat exchanger 1 is poor, so the temperature of the medium oil in the heat exchange pipe 3 is 250 The temperature of the medium oil in the heat exchange pipe 3 may be controlled to 250 ° C. or more and 310 ° C. or less. Thus, by controlling the temperature of the medium oil in the heat exchange pipe 3 of the heat exchanger 1, corrosion of the heat exchange pipe 3 can be suppressed, and the life of the heat exchange pipe 3 can be extended. And the efficiency of the heat exchanger 1 is also good.

  Although the combustion apparatus shown in FIG. 1 is provided with a grate 11 for supplying air to the bottom of the combustion furnace 10 and supplies combustion air from the bottom, the form of the combustion furnace 10 is not limited to this, The present invention is applicable to various combustion furnaces 10.

  Moreover, in the above-mentioned embodiment, although demonstrated about the case where bamboo was used as a biomass raw material containing chlorine, the biomass raw material containing other chlorine can also apply this invention.

1: Heat exchanger 2: Bamboo chip (biomass fuel containing chlorine)
3: heat exchange piping 10: combustion furnace 11: grate 11a: hole 12: lid 12a: inlet 13: exhaust pipe 14: inlet 31: temperature detector 32: temperature controller 32a: temperature detector 32b: flow rate Adjustment device

Claims (3)

A heat exchange pipe made of steel material for circulating a medium liquid is provided in a combustion furnace, and the combustion exhaust gas produced by burning a biomass fuel containing chlorine in the combustion furnace is brought into contact with the heat exchange pipe to heat the medium liquid. Heat exchanger, and
Outflow side temperature detection means for detecting the temperature of the medium liquid flowing out of the heat exchanger, and provided on the side flowing into the heat exchanger, for heat exchange according to the detection output of the outflow side temperature detection means And temperature control means for adjusting the temperature of the medium liquid in the pipe, and the temperature control means causes the temperature of the medium liquid in the heat exchanger to flow out of the heat exchanger so that the temperature of the medium liquid is in the range of hydrochloric acid dew point to 400 ° C. A heat exchanger characterized by controlling the temperature of the medium fluid to 250 ° C. or more and 310 ° C. or less . In the heat exchanger according to claim 1,
The temperature control means includes an inflow side temperature detection means for detecting the temperature of the medium fluid flowing into the heat exchanger, and a flow control means for controlling the flow rate of the medium fluid flowing into the heat exchanger. A heat exchanger characterized in that the flow rate control means controls the flow rate of the medium liquid flowing into the heat exchanger according to the outputs of the outflow side temperature detection means and the inflow side temperature detection means. In the heat exchanger according to claim 1 or 2 ,
The heat exchanger characterized in that the biomass fuel is a bamboo material.

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