JP6208970B2 - Power generation method - Google Patents

Description

  The present invention relates to a power generation method using a fluidized bed boiler that efficiently uses palm coconut seed shells produced and discarded in large quantities.

In recent years, the global warming phenomenon associated with an increase in emissions of carbon dioxide and the like has become a problem. The main reason for this is the use of fossil fuels such as oil and coal. In addition, the reserves of these fossil fuels are limited, and various energy sources to replace oil and coal are being studied.
Biofuels derived from biomass are being considered as the above energy sources, but corn, sugarcane, wheat, etc., which are used as raw materials, are also used for food, so what is the best method in terms of ecosystem and economic balance? I can't say that. Attempts have also been made to produce solid fuel from waste biomass such as wood chips, waste materials, and sugarcane pomace, but due to reasons such as low bulk density, poor storage and transport efficiency, and low calorific value per unit volume. Its use is limited.

On the other hand, in nature, there are fruits (especially seeds) that are not edible but have a relatively high content of fat and oil components. Many oils and fats are extracted from the fruit (seed) and used in soaps and industrial products. For example, sesame seeds are used as a raw material for castor oil. }; Nanjing yellow cocoon (also known as Tohaze and Kanteragi), which uses oil and fat from seeds as a raw material for soap and candles; Nanyang oil paulownia (also known as Thai Wan Abagiri, Jatropha or Jatropha); rapeseed (commonly known as oil rape); palm (coconut palm) (generic term for palm family plants) where fats and oils are used for industrial use, soap, margarine, etc .; In addition, starch (corn starch), oil, and corn, which is important as a raw material for bioethanol, can be mentioned.
In addition to coco palm as the above palm, there is palm palm, and palm oil obtained by pressing from the palm palm pulp is the world's second largest production after soybean oil, margarine, shortening, cake, instant ramen, Applications are expanding as soaps and surfactants, and their production is expanding. Seeds are separated from the oiled pulp, the seeds are shelled, and palm kernel oil is further extracted from the endosperm.
This seed husk is called palm coconut seed husk, and the calorific value at the time of combustion is 4400 kcal / Kg, which is higher than that of wood chips. The hard glove coefficient is 14 and it is difficult to pulverize. With the increase, about 4 million tons of palm coconut seed husks are generated annually, and the treatment becomes a problem. The palm palm seed shell is used for activated carbon and the like, but its usage is small. As one of the means for processing in large quantities, thermal power generation using mixed combustion with coal has been studied and a demonstration test has been conducted.

JP 2003-268394 A

Palm palm seed husks are hard as described above and difficult to grind, and therefore are not suitable for co-firing in pulverized coal thermal power generation. In order to perform co-firing, a method of pulverizing and reducing the particle size in advance and then pulverizing and mixing with coal using a coal pulverizer has been adopted.
This method is a fine method in which both are finely pulverized and excellent in combustibility. However, in order to finely pulverize palm coconut seed shells, a device combined with a hammer mill and a vibrating screen is required, which requires a large amount of equipment. This not only increases the energy cost, but also causes the vibration screen to be clogged in a short time, making it difficult to perform stable continuous operation, resulting in problems in practical use. In addition, in the conventional vertical mill, efficient pulverization has been difficult due to lightness and elasticity of palm palm seed shells (Patent Document 1).

  As a result of intensive research on a method of generating electricity by co-firing palm coconut seed husk with pulverized coal, the present inventors put unpulverized palm coconut seed husk together with coal into a pulverizer to determine the predetermined coal. When pulverized into coarse-grained coal with a particle size, palm coconut seed husks are not pulverized as much as coal and remain as a relatively large particle size, but become a uniform mixture and phase separation is unlikely to occur. It was found that not only combustion efficiency is high but also NOx and SOx generation does not increase by efficiently burning in a boiler furnace, and the present invention has been achieved.

The present invention has been achieved based on the above knowledge, and according to the present invention, coal and uncrushed palm coconut seed shell are combined with 100 parts by mass of coal. was charged into the crusher so that the ratio of from 15 to 500 parts by mass relative to the particle size of the coal, sieve residue less than 5 wt% of the mesh 5 mm × 5 mm, residue sieve mesh 1.78 mm × 1.78 mm There is provided a power generation method characterized by co-pulverizing to 30 to 70% by mass, supplying the obtained co-ground product directly to a furnace of a fluidized bed boiler and burning it, and generating electric power with the generated steam. .
In the invention of the power generation method,
1) A circulating fluidized bed boiler is used as the fluidized bed boiler, and a solid particle circulation in which a part of the uncrushed palm palm seed husk is recovered and solid particles in the exhaust gas of the circulating fluidized bed boiler are recovered and circulated to a furnace. Supply to the furnace without crushing and supply to the furnace with solid particles,
2) Before subjecting to the co-grinding, use uncrushed palm palm seed husks by collecting the sieve passage of mesh 30 mm × 30 mm to mesh 50 mm × 50 mm,
3) The uncrushed palm palm seed husks are stored so that the water content is maintained at 15% by mass or more in the storage area;
Is preferred.

According to the present invention, palm coconut seed husks that are produced and discarded in large quantities can be used for co-fired thermal power generation with coal, and can be consumed in large quantities without being wasted. It is.
Also, by co-pulverizing coal with low energy enough to pulverize to a normal degree of pulverization, it is possible to supply in a uniform mixed state, and it is necessary to spend a lot of energy to pulverize palm palm seed shells In addition, the combustion efficiency after being introduced into the furnace is high, and the generation amount of NOx and SOx does not increase, and power generation can be performed stably, which is an industrially excellent invention.

The figure which shows typically the aspect which implements this invention using a fluidized-bed boiler electric power generating apparatus. It is a figure which shows the amount of generated steam in Example 1. FIG. 3 is a graph showing the amount of NOx, SOx, and dust generated in Example 1. It is a figure which shows the amount of generated steam in Example 2. FIG. It is a graph which shows the generation amount of NOx, SOx, and dust in Example 2. It is a figure which shows the amount of generated steam in the comparative example 1. 6 is a graph showing the amount of NOx, SOx, and dust generated in Comparative Example 1.

The fluidized bed boiler power generator of the present invention is a conventionally known device, and can be used without any limitation.
A typical fluidized bed boiler power generator mainly includes a supply port for supplying mixed fuel and a furnace having a fluidized bed at the lower part; a convection heat transfer unit for supplying high-temperature combustion gas from the furnace and generating steam by heat exchange. It is to be configured. Preferably, a circulating fluidized bed boiler power generator comprising a cyclone for collecting particles discharged accompanying combustion gas from a furnace and a solid particle circulation path for returning the particles separated by the cyclone to the furnace. Is preferred. Furthermore, it is preferable that the solid particle circulation path has a sub fuel inlet for introducing fuel other than coal, for example, tire pieces or unpulverized or partially pulverized palm coconut seed shells and burning them in a furnace. FIG. 1 shows a typical circulating fluidized bed boiler power generator.

Palm coconut seed husks transported from the production area often contain foreign substances such as palm coconut bunches, palm coconut fiber, stones, and wood chips. These foreign substances cause clogging in the subsequent process, and further coal It is preferable to remove them in advance because they hinder co-grinding and combustion in a fluidized bed boiler. The removal method is not particularly limited, but a simple method is to apply an uncrushed palm palm seed shell to a sieve of mesh 30 mm × 30 mm to mesh 50 mm × 50 mm (JIS standard 3553, JIS symbol CR-S) and collect the passing portion. Moreover, it has a sufficient removal effect.
In addition, it is preferable from the viewpoint of dust generation that the uncrushed palm palm seed husk is maintained at a water content of 15% by mass or more when stored in a storage area. The water content is preferably controlled by installing a water spray in a storage area and controlling the amount of water supplied to the water spray.

Palm coconut seed shells obtained by the above treatment are put into a pulverizer together with coal and co-ground and mixed. Due to this co-grinding, the coal has a particle size of less than 5% by mass of mesh 5 mm × 5 mm sieve residue, 30-70% by mass of mesh 1.78 mm × 1.78 mm sieve residue, preferably 40-60% by mass. It is co-ground so that
On the other hand, the palm coconut seed shell, which is hard to be crushed, has a particle size after co-grinding that is slightly larger than that of coal, which is only about 2.5 to 10 mm, and the shape after pulverization is not uniform. is there. In the pulverized state of the above level, the palm palm seed husks are uniformly mixed with the coarse coal, do not undergo phase separation, can perform stable combustion, and have high combustion efficiency.
The mixing ratio of the co-ground coal and palm palm seed shell is usually 15 to 500 parts by weight of palm palm seed shell with respect to 100 parts by weight of coal. When the mixing ratio with the palm palm seed shell exceeds 500 parts by mass, the total amount of heat generated by the boiler tends to decrease.
As will be described later, the palm palm seed husk can be used as a secondary fuel by collecting solid particles in the exhaust gas and throwing them into a solid circulation path circulating in a furnace without being pulverized. In that case, it is preferable to use it so that the total amount of the palm cocoon seed husk used for the co-grinding and the palm coconut seed husk of the auxiliary fuel may fall within the above range. Moreover, in this case, it is preferable to adjust the ratio of palm coconut seed shells used as the auxiliary fuel to be 30% by mass or less of the total amount.

As a pulverizer used for co-pulverization, a known crusher such as a hammer crusher is used without particular limitation, and control of coal coarse powder carbonization is usually performed by adjusting the pulverization speed and clearance.
The measurement of the particle size of the coal after the co-grinding is performed by sampling the co-pulverized product after pulverization in an arbitrary amount, for example, about 1 kg, 10 times. A method of obtaining an average value by applying a sieve of 78 mm × 1.78 mm and visually selecting the co-pulverized product obtained by sieving into coal and PKS, measuring the respective weights, and the like was adopted.
In addition, in the above-mentioned degree of pulverization, as described above, the palm coconut seed shell has a particle size after co-grinding that is slightly larger than that of coal, and the mesh passage of 1.78 mm × 1.78 mm is as follows. , Almost negligible.
Therefore, regarding the particle size of coal in the co-ground product, the mass of coal selected from the mesh residue of 5 mm × 5 mm (C _5R ), the mass of coal selected from the mesh residue of 1.78 mm × 1.78 mm ( C _1.78R ), when the mass of coal passing through a sieve with a mesh of 1.78 mm × 1.78 mm (C _1.78P ), the ratio of the remaining mesh of the coal mesh 5 mm × 5 mm (CR ₅ ), and The ratio (CR _1.78 ) of the sieve residue of _1.78 mm × _1.78 mm mesh can be obtained by the following equation.
CR ₅ = C _5R / (C _5R + C _1.78R + C _1.78P ) × 100
CR _1.78 = C _1.78R / (C _5R + C _1.78R + C _1.78P ) × 100
Moreover, about the particle size of the palm palm seed shell in a co-ground material, the mass (P _5R ) of the palm palm seed shell selected from the mesh residue of 5 mm × 5 mm, and the screen residue of the mesh 1.78 mm × 1.78 mm When the mass of the palm palm seed husk (P _1.78R ) is taken, the ratio of the palm _cocoon seed shell mesh 5 mm × 5 mm sieve residue (PR ₅ ) and the mesh 1.78 mm × 1.78 mm sieve residue The ratio (PR _1.78 ) can be obtained by the following equation.
PR ₅ = P _5R / (P _5R + P _1.78R ) × 100
PR _1.78 = P _1.78R / (P _5R + P _1.78R ) × 100

The mixed fuel of co-ground and mixed coal and palm coconut seed husks is temporarily stored in a fuel bunker and can be appropriately put into the lower part of the fluidized bed boiler furnace for combustion by a coal feeder located at the bottom of the bunker. preferable.
In the present invention, well-known and well-known techniques can be employed without any limitation with respect to the structure, devices, and members of steam generation such as fluidized bed boilers and steam pipes, as well as power generation using the steam.

  In the present invention, the mixed fuel as described above is directly supplied to the fluidized bed portion of the furnace and combusted. During the combustion, the solid particles in the exhaust gas of the circulating fluidized bed boiler are collected and circulated to the furnace. The uncrushed palm palm seed husk may be supplied to the solid circulation path as an auxiliary fuel without being crushed, and may be put into the furnace together with the solid particles. In addition to the palm coconut seed shell, other auxiliary fuel such as a tire piece can be used for the supply to the solid particle circulation path.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not restrict | limited at all by these Examples. In addition, not all combinations of features described in the embodiments are essential to the solution means of the present invention.

Example 1
Using the circulating fluidized bed boiler shown in FIG. 1, the palm palm seed shell ratio is 22 parts by mass with respect to 100 parts by mass of coal, and the pulverized material co-ground with a hammer crusher is directly applied to the circulating fluidized bed boiler furnace. The results when supplied and burned are shown in FIGS.
The pulverizer used a hammer crusher with a capacity of 150 tons / hr, and co-ground coal and palm palm seed shells at a pulverization amount of 35 tons / hr. The ratio of coal and palm palm seed shell in the co-pulverized product was 20 parts by mass of palm palm seed shell with respect to 100 parts by mass of coal.
The coal in the co-ground product had a mesh residue of 5 mm × 5 mm of 1.5% by mass, and a mesh residue of 1.78 mm × 1.78 mm was 52% by mass. The palm palm seed shell at that time was one size larger than coal, and the mesh residue of 5 mm × 5 mm was 38% by mass.
As shown in FIG. 2, when palm palm seed husks are co-fired, a predetermined amount of steam can be obtained in the same manner as in the case of coal-only firing, and as shown in FIG. 3, the amount of NOx, SOx and dust generated is large. It was confirmed that there was no change.
In the present embodiment, since most of the SOx generated is SO _2, in FIG. 3 shows only the measurement values of SO ₂ of the SOx. Similarly, in the following examples and comparative examples, only the measured value of SO ₂ was shown.

Example 2
Using the circulating fluidized bed boiler shown in FIG. 1, the ratio of the palm palm seed shell is 60 parts by mass with respect to 100 parts by mass of coal, and the pulverized material co-ground with a hammer crusher is used as the furnace of the circulating fluidized bed boiler. The results when directly supplied and burned are shown in FIGS.
As the pulverizer, the same hammer crusher as in Example 1 was used, and coal and palm palm seed husk were co-ground at a pulverization amount of 35 tons / hr. The ratio of coal and palm palm seed husk in the co-pulverized product was 57 parts by mass of palm palm seed husk with respect to 100 parts by mass of coal.
The coal in the co-ground product had a mesh residue of 5 mm × 5 mm of 1.2% by mass and a mesh residue of 1.78 mm × 1.78 mm was 49% by mass. The palm palm seed shell at that time was one size larger than coal, and the mesh residue of 5 mm × 5 mm was 42% by mass.
As shown in FIG. 4, when coal, palm coconut seed husks and tire chips are co-fired, a predetermined amount of steam can be obtained in the same manner as when coal and tire chips are co-fired. As shown in FIG. It was confirmed that there was no significant change in the amount of SOx and SOx generated.

Example 3
Using the circulating fluidized bed boiler shown in FIG. 1, the ratio of the palm palm seed shell is 60 parts by mass with respect to 100 parts by mass of coal, and the pulverized material co-ground with a hammer crusher is used as the furnace of the circulating fluidized bed boiler. Direct feeding and burning.
As the pulverizer, the same hammer crusher as in Example 1 was used, and coal and palm palm seed husk were co-ground at a pulverization amount of 35 tons / hr. In order to confirm the effect of changing the coal particle size, the coarseness of the coal was increased. The ratio of coal and palm palm seed shell in the co-pulverized product was 58 parts by mass of palm palm seed shell with respect to 100 parts by mass of coal.
The coal in the co-ground product had a mesh residue of 5 mm × 5 mm of 2.3% by mass and a mesh residue of 1.78 mm × 1.78 mm was 58% by mass. The palm palm seed shell at that time was one size larger than coal, and the sieve residue of 5 mm × 5 mm mesh was 45% by mass.
As in the case of Example 2, it was possible to obtain a predetermined amount of steam, and it was confirmed that there was no significant change in the amount of NOx, SOx, and dust generation.

Example 4
Using the circulating fluidized bed boiler shown in FIG. 1, the ratio of the palm palm seed shell is 60 parts by mass with respect to 100 parts by mass of coal, and the pulverized material co-ground with a hammer crusher is used as the furnace of the circulating fluidized bed boiler. Direct feeding and burning.
As the pulverizer, the same hammer crusher as in Example 1 was used, and coal and palm palm seed husk were co-ground at a pulverization amount of 35 tons / hr. In order to confirm the effect of changing the coal particle size, the coarseness of the coal was refined. The ratio of coal to palm coconut seed shell in the co-pulverized product was 55 parts by mass with respect to 100 parts by mass of coal.
The coal in the co-ground product had a mesh residue of 5 mm × 5 mm of 0.6% by mass and a mesh residue of 1.78 mm × 1.78 mm was 43% by mass. The palm palm seed shell at that time was one size larger than coal, and the mesh residue of 5 mm × 5 mm was 38% by mass.
As in the case of Example 2, it was possible to obtain a predetermined amount of steam, and it was confirmed that there was no significant change in the amount of NOx, SOx, and dust generation.

Comparative Example 1
As a comparative example, using the circulating fluidized bed boiler shown in FIG. 1, without crushing 22 parts by mass of unpulverized palm palm seed shells with respect to 100 parts by mass of coal, as a secondary fuel from the solid particle circulating furnace, FIGS. 6 and 7 show the results when the fuel is introduced into the furnace together with the solid particles.
The main fuel was only coal, and the pulverizer used the same hammer crusher as in Example 1 to pulverize the coal at a pulverization amount of 30 tons / hr. As for the particle size of the coal, the sieve residue of mesh 5 mm × 5 mm was 1.8 mass%, and the sieve residue of mesh 1.78 mm × 1.78 mm was 55 mass%.
As shown in FIG. 6, when palm palm seed husks were introduced from the solid particle circulation path, a predetermined amount of steam could be obtained in the same manner as in the case of coal-fired, but as shown in FIG. The amount of NOx generated did not change greatly, but NOx increased by about 30 ppm.

Claims (4)

The coal and uncrushed palm palm seed husk are charged into a pulverizer at a ratio of 15 to 500 parts by mass with respect to 100 parts by mass of the coal. Are co-pulverized so that the mesh residue is less than 5% by mass of 5 mm × 5 mm and the residue of 30-70% by mass of mesh 1.78 mm × 1.78 mm is obtained, and the obtained co-pulverized product is fluidized bed boiler. A power generation method characterized in that power is directly supplied to the furnace and burned, and power is generated with the generated steam. A circulating fluidized bed boiler is used as the fluidized bed boiler , and a part of the uncrushed palm coconut seed shell and solid particles in the exhaust gas of the circulating fluidized bed boiler are collected and pulverized into a solid particle circulation path circulating in a furnace. The power generation method according to claim 1, wherein the electric power is supplied without being supplied to the furnace together with the solid particles. The power generation method according to claim 1 or 2 , wherein an uncrushed palm coconut seed shell is collected and used after passing through a sieve of mesh 30 mm x 30 mm to mesh 50 mm x 50 mm before being subjected to the co-grinding. The power generation method according to any one of claims 1 to 3 , wherein the uncrushed palm palm seed husk is stored so as to maintain a water content of 15 mass% or more in the storage field.