JP2016222781A - Hydrogen production method and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen production method and system which can highly efficiently produce high-purity hydrogen directly from cellulose or sewage sludge as a biomass resource.SOLUTION: Calcium hydroxide and nickel hydroxide are mixed with cellulose or sewage sludge as a biomass resource and the mixture is heated to produce hydrogen. In the case where the heat treatment temperature is 700-850°C, the biomass resource, calcium hydroxide and nickel hydroxide are mixed in the mixed molar ratio of 1:(0.01 (not zero) to 3.0):( 0.01 (not zero) to 1.0) and crushed and kneaded, the mixture is supplied to an external furnace and heat-exchanged with hot air to raise its temperature, and various produced gases produced by a heating reaction during temperature rising are decreased in temperature and dehumidified, and a part thereof is introduced into a continuous gas analyzer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydrogen production method and system for producing hydrogen gas used as various energy sources from biomass resources.

  Since the Great East Japan Earthquake, there has been a strong social and economic impact due to the shortage of power supply, and it has been strongly desired to secure safe and stable energy supply. On the other hand, the construction of a low-carbon society is strongly desired to prevent global warming from the viewpoint of environmental conservation.

  Therefore, hydrogen energy is attracting attention. Extraction of electricity and heat from hydrogen by a fuel cell is a popular technology, and hydrogen is promising as an energy carrier because it has a high energy density per weight and can be stored. Further, when pure hydrogen is used in a fuel cell, it is a clean fuel because it does not discharge air pollutants.

  Hydrogen is used as a raw material for many products such as ammonia production, hydrochloric acid production by mixing with chlorine gas, light irradiation, solidification by reducing double bonds together with fats and oils, and corn oil and margarine production. As specific examples, hydrogen is a reduction of metal ore, a reduction of nitrobenzene in the production of aniline, a catalytic reduction of benzene in the production of nylon 66, a fuel for internal combustion engines such as rocket fuel and hydrogen automobile, and various fuels. It is used as an energy source as battery supply gas.

  As a conventional hydrogen gas production method, for example, as shown in Patent Document 1, aluminum or an aluminum alloy is rubbed and crushed in water to form fine particles of 50 μm or less, and then the temperature or ultrasonic impact is applied to the fine particles. There is a method in which after the heat treatment at room temperature for several days, the fine particles are cooled to 5 ° C. and placed in a storage state to react with water molecules at room temperature.

  Furthermore, as disclosed in Patent Document 2, in the method for producing hydrogen gas from biomass, plants, those produced from plants, waste paper, livestock excrement, food waste, building generated wood, or sewage sludge A predetermined amount of high cellulose-containing powder, calcium hydroxide powder, and nickel hydroxide powder, which are waste materials, are weighed, and the weighed material and a plurality of hard balls are placed in a mixing container and mixed and pulverized for a predetermined time. Then, the prior art of the present applicant is that the mixed pulverized product is heated and held in a sealed container at a temperature of 350 ° C. or higher and 450 ° C. or lower to derive the generated hydrogen gas.

Japanese Patent No. 4169197 Japanese Patent No. 5170516

  However, about 80% of hydrogen is produced by a steam reforming reaction using petroleum or natural gas as a resource. In this reaction, a high temperature of about 800 to 1000 ° C. is necessary, and the generated gas generates carbon monoxide, carbon dioxide, methane, etc. in addition to hydrogen. A gas separation operation is required for recovery. These fossil fuels as hydrogen sources will not be able to be mined permanently and will eventually be depleted.

  In recent years, natural energy such as solar power generation and wind power generation has attracted attention as a renewable energy utilization technology, but there remains a problem in terms of stable power supply. Power generation using local woody biomass is also being introduced gradually, but since it is essential to build a system that includes the collection and transportation of woody biomass as a raw material, stable supply during the decades of business has become an issue .

  Also, when plastic is used as the hydrogen source, considering that it is originally manufactured from fossil fuels, it is urgent to develop alternative resources for hydrogen sources from the perspective of preserving fossil fuel resources and preventing global warming. It is peeling off. Therefore, there are great expectations for woody biomass, plastic waste, etc. as a source of hydrogen generation.

  Moreover, in the above-mentioned Patent Document 1, a large-scale cutting device for rubbing and pulverizing aluminum or an aluminum alloy in water is necessary, and continuous operation for producing high-efficiency and high-purity hydrogen. It was difficult to realize a hydrogen gas production apparatus by

  Furthermore, in the case of the above-mentioned Patent Document 2 by the present applicant, a mixed sample (weight 3 g) of cellulose, calcium hydroxide and nickel hydroxide is mixed and pulverized using a planetary mill and a steel ball as a mechanochemical treatment. The processed powder is heated, evaluated by a mass spectrometer, and the generated gas is qualitatively analyzed. This is also a high-efficiency and high-purity directly from, for example, cellulose or sewage sludge as a biomass resource. In order to continuously produce hydrogen, the heat treatment temperature may be 350 ° C. or higher and 450 ° C. or lower, and the continuous operation rate may be low, and there is room for further improvement. there were.

  Therefore, the present invention was created in view of the existing circumstances as described above, and without using a conventional fossil fuel resource reforming reaction, as a biomass resource, for example, cellulose, sewage sludge, etc. An object of the present invention is to provide a hydrogen production method and system capable of continuously producing high-efficiency and high-purity hydrogen directly from the above.

  In order to solve the above-described problems, in the present invention, as a biomass resource, calcium hydroxide and nickel hydroxide are mixed with cellulose and sewage sludge (treated as the same unit molar mass as cellulose from the elemental composition) and heated. In this way, hydrogen is produced.

  When the heat treatment temperature is 700 ° C. to 850 ° C., the mixing molar ratio of the biomass resource, calcium hydroxide, and nickel hydroxide is 1: (0.01 (not zero) to 3.0) :( 0. 01 (not zero) to 1.0).

  Mixing means for mixing calcium hydroxide and nickel hydroxide in a predetermined molar ratio to cellulose and sewage sludge (treated as the same unit molar mass as cellulose from the elemental composition) as a biomass resource, and crushing and kneading, and said crushing・ A heat treatment means for supplying the kneaded mixture to an external heating furnace and exchanging heat with hot air to raise the temperature, and reducing and dehumidifying various product gases generated by the heating reaction at the time of the temperature rise, and a part thereof Hydrogen is produced by a hydrogen production apparatus having a dehumidifying and dehumidifying means to be introduced into the gas analyzer.

  In the present invention, a technique for directly producing hydrogen has been developed by mixing biomass resources with calcium hydroxide and nickel hydroxide and heating them. On the other hand, the development of various conversion technologies has been reported, focusing on the fact that sewage is built into social infrastructure and sewage sludge is a permanently generated biomass resource. Therefore, by applying these development technologies, we attempted batch-type hydrogen production from sewage sludge, and succeeded in producing high-purity hydrogen directly from sewage sludge without using the usual reforming reaction of fossil fuel resources. Applying this technology, in order to introduce a practical plant that produces high-purity hydrogen with high efficiency, the basic concept and design of the demonstration plant are ascertained with a laboratory-level continuous hydrogen production tester to understand the scale-up factors. It is connected.

  According to the present invention, without using a conventional fossil fuel resource reforming reaction or the like, high-efficiency, high-purity hydrogen is continuously produced directly from, for example, cellulose or sewage sludge as a biomass resource. be able to.

It is a flow block diagram which shows the flow of a process in schematic structure of the hydrogen production test apparatus which shows one form for implementing this invention. It is explanatory drawing which showed the experimental result of the influence which the mixing amount of calcium hydroxide and nickel hydroxide has on the amount of hydrogen generation. It is explanatory drawing which shows the test result of the hydrogen generation amount under the influence of the amount of sewage sludge retention by the presence or absence of an exit weir when processing temperature is made constant at 700-850 degreeC, and a total supply amount is made constant at 12 kg / h. is there. It is explanatory drawing which shows the test result of the amount of hydrogen generation performed by making process temperature constant at 700-850 degreeC and changing the mixture ratio and total supply amount when sludge is set to 1. FIG. It is a case where a device for dropping water is provided in front of the kneading section and quantitative supply is performed, (a) is an explanatory diagram for explaining the experimental conditions, and (b) is a graph showing the experimental results. This is a case where a device for dropping water is provided in front of the kneading section, and the quantitative supply amount is lowered by half, (a) is an explanatory diagram for explaining the experimental conditions, and (b) is a graph showing the experimental results FIG. It is explanatory drawing which shows the experimental result at the time of optimizing a continuous hydrogen generation reaction on the basis of 700-850 degreeC of process temperature, a total supply amount of 6 kg / h, and having a weir. It is explanatory drawing which put together the conclusion from the introduction effect examination of a practical plant as a table | surface.

  Hereinafter, embodiments of the present invention will be described in detail.

Hereinafter, embodiments of the present invention will be described in detail. In the present embodiment, an external heating type continuous operation hydrogen production test apparatus P as shown in the flow configuration of FIG. 1 was designed and manufactured, and experiments were performed under various conditions. That is, as shown in FIG. 1, the apparatus P includes a first fixed supply hopper 1 for feeding calcium hydroxide Ca (OH) ₂ , a second fixed supply hopper 2 for feeding dehydrated sludge, and nickel hydroxide Ni (OH ) ₂ 3 metering hopper 3 for introducing a calcium hydroxide from the metering hopper 1, 2, 3, dewatered sludge, biaxial kneading screw 4 (mixing means nickel hydroxide, each of which is filled), the two- An external heating furnace 7 (heat treatment) having a jacket / shell structure for heat treatment in which calcium hydroxide, dehydrated sludge and nickel hydroxide are introduced from the shaft kneading screw 4 through an inlet seal 5 and a nitrogen feeder 6. Means).

  The external heating furnace 7 is connected to a hot air generation furnace 8 that generates hot air using outside air and LPG. Further, the external heating furnace 7 is a water spray type condenser and a cooling water circulation type condenser 9 (temperature reduction and dehumidification means). And an exhaust fan 10. Further, the external heating furnace 7 collects the processed material after combustion as a sample via the outlet seal 11. The condenser 9 is connected to a circulating water tank 13 capable of exhausting and draining through a carbonization furnace exhaust damper 14 and a water ejector 15, and the condenser 9 is for exhausting and analyzing the generated gas at the same time. It is connected to the regulating pump 12.

<Flow of processed material>
Calcium hydroxide, dehydrated sludge, and nickel hydroxide as raw materials are filled in the respective quantitative supply hoppers 1, 2, and 3, and are cut out by a cutting machine (not shown) to a weight that provides the molar ratio of the experimental conditions. The biaxial kneading screw 4 is filled. The raw materials are sequentially conveyed by the twin-screw kneading screw 4, crushed and kneaded by the pin screw portion 4a, and supplied to the external heating furnace in a well kneaded state. The raw material supplied to the external heating furnace 7 is heated up by exchanging heat with the hot air in the jacket of the external heating furnace 7, and the reaction proceeds and hydrogen gas (H ₂ ), methane gas (CH ₄ ), carbon monoxide (CO) Generate various gases such as carbon dioxide (CO ₂ ) and oxygen (O ₂ ). After processing, the sample is recovered as a processed product.

<Flow of heat source gas>
The supplied hot air is taken into the hot air generating furnace 8 and is heated to a predetermined temperature by LPG. After the temperature rise, the air is supplied to the jacket of the external heating furnace 7, exchanges heat with the shell of the external heating furnace 7, and the hot air whose temperature has dropped is exhausted by the exhaust fan 10.

<Flow of generated gas>
Since the gas generated by the reaction in the external heating furnace 7 contains a large amount of water vapor, it is dehumidified by the condenser 9 and then sucked by the water ejector 15 and submerged in water, and then released to the atmosphere. A part of the product gas is introduced into the suction analyzer by the adjusting pump 12, and the gas analysis is continuously performed.

<Evaluation of product>
FIG. 2 shows the influence of the mixing amount of calcium hydroxide and nickel hydroxide on the hydrogen generation amount. When the mixing amount of nickel hydroxide is increased from 0 mol to 0.1 mol and 1 mol in the mixing amount of calcium hydroxide, the amount of hydrogen generation also increases. In addition, at 0 mol without nickel hydroxide, the amount of hydrogen generation increases monotonously when the mixing ratio of calcium hydroxide is increased. On the other hand, when 0.1 mol and 1 mol of nickel hydroxide are mixed, the amount of hydrogen generated is maximum at 38 g / kg and 74 g / kg per unit when calcium hydroxide is 1 mol and 3 mol, respectively. On the other hand, it was found that there was an optimum mixing amount of calcium hydroxide.

<Evaluation of product when dry sludge is used>
As shown in FIG. 3, since the amount of stay increased due to the provision of the outlet weir, the processing time in the machine was extended, and the amount of generated gas was greatly improved. That is, when the heat treatment temperature is 700 to 850 ° C. and the total supply amount is 12 kg / h, the generated gas amount is 7.0 L / min, the hydrogen generation amount per unit is 12.9 g / kg, the hydrogen gas concentration is 61. Whereas it was 35 vol%, in the presence of weirs, the generated gas amount was 23.1 L / min, the hydrogen generation amount per unit was 42.7 g / kg, and the hydrogen gas concentration was 61.37 vol%. Therefore, the subsequent tests were conducted with a weir. Further, since there was no significant difference in the hydrogen concentration in the gas, the hydrogen concentration in the gas is considered to depend on the processing temperature.

<Clarification of the effect of the mixing ratio of each raw material>
The test was conducted by changing the blending ratio and the total supply amount when the treatment temperature was 700 to 850 ° C. and the sludge was 1 mol. As a result, as shown in FIG. 4, when calcium hydroxide is 1 mol or nickel hydroxide is 0.01 mol, the amount of hydrogen generation is greatly reduced, calcium hydroxide is about 2 mol, and nickel hydroxide is 0 It was found that about 5 mol was necessary. However, the amount of hydrogen generated per unit is still low and further operation is required.

<Clarification of the effect of water addition to raw materials>
In the basic test, there was a result that the amount of hydrogen generation was increased by about 2.5 times by adding water. Therefore, even in this testing machine, before or near the kneading part of the biaxial kneading screw 4 ( For example, a water dripping device (see FIG. 1) was provided in the pin screw portion 4a), and a fixed amount was supplied.

  FIG. 5A shows experimental conditions for clarifying the influence of water addition. That is, the heat treatment temperature is 700 to 850 ° C., sludge: calcium hydroxide: nickel hydroxide = 1: 2: 0.5 (molar ratio), total supply amount is 12 kg / h, weir, water The supply amounts are 1.25 kg / h (water addition rate 50%) and 0.6 kg / h (water addition rate 25%).

  As a result, as shown in FIG. 5 (b), 1.25 kg / h of water corresponding to 50% of the sludge anhydrous weight was supplied and the change was observed at time 14:20. Because of the increase, the pressure balance inside the aircraft was lost and leaked air increased. As a result, an increase in the flow rate at the inlet of the analyzer was observed, but this caused an increase in the oxygen concentration, and because the gas in the hazardous area was sampled by the analyzer, the nitrogen purge was repeated. Thereafter, at time 15:43, the water supply amount was lowered to 0.6 kg / h corresponding to 25% of the sludge anhydrous weight, but the collapsed pressure balance could not be recovered. Since the change in pressure balance due to the supply of water may not be able to cope with the required supply heat quantity that increases with the increase in the amount of evaporated water, the supply quantity of the tester is reduced to half, and FIG. The test was conducted under the experimental conditions for clarifying the influence of water addition shown in a). That is, the heat treatment temperature is 700 to 850 ° C., sludge: calcium hydroxide: nickel hydroxide = 1: 2: 0.5 (molar ratio), the total supply amount is 6 kg / h, weir, water The supply amounts are 0.16 kg / h (water addition rate 15%) and 0.52 kg / h (water addition rate 50%).

  As a result, as shown in FIG. 6 (b), water was supplied at 0.16 kg / h corresponding to 15% of the sludge anhydrous weight from time 13:23, and the change was observed. Although the hydrogen concentration increased, the hydrogen concentration decreased, and the change stopped at around 16:00, and the analysis inlet exhaust flow rate and hydrogen concentration were about the same as when the gas was not supplied. Therefore, although the supply amount of water was increased to 0.52 kg / h corresponding to 50% of the sludge anhydrous weight from time 16:14, the flow rate increased and the hydrogen concentration decreased temporarily. After that, the pressure balance was lost, hunting by nitrogen purge was caused for a while, and then it was picked up, but it stayed at the same value as when not supplied.

  As a result, in the continuous reaction, an increase in the amount of hydrogen generated due to the supply of water could not be confirmed. This is probably because the large amount of steam generated from the constantly supplied dewatered sludge has an effect equivalent to the dripping of water in basic research, and the supply of more water does not contribute to the reaction.

<Optimization of reaction in continuous system>
In the clarification of the influence of water addition to the raw materials described above, there was a possibility that the amount of heat required for the reaction was more than the amount of heat originally assumed. Therefore, in this embodiment, based on the heat treatment temperature of 700 to 850 ° C., the total supply amount of 6 kg / h, and the presence of the weir, the mixing ratio of the catalyst usage amount that is the cheapest in terms of running cost in basic research is Since it was shown that calcium oxide: nickel hydroxide = 1: 2: 0.5 (molar ratio), optimization was performed based on this.

  When sludge: calcium hydroxide: nickel hydroxide = 1: 2: 0.5 (molar ratio), the carbon dioxide concentration was high, so that 2.5 mol of calcium hydroxide was added to promote the reaction. The cut-out amount was adjusted so as to obtain a blending ratio. However, since the amount of sludge cut out fluctuated and the supply amount increased, as shown in FIG. 7, optimization was performed with the blending ratio when sludge increased. At this time, the reaction was accelerated and an increase in the hydrogen concentration was observed. That is, sludge: calcium hydroxide: nickel hydroxide = 1: 2.2: 0.45 (molar ratio), total supply amount 6.82 kg / h, generated gas amount 14.1 L / min, per unit The hydrogen generation amount was 43.3 g / kg, and the hydrogen gas concentration was 66.2 vol%. In addition, the amount of generated gas may have increased due to an increase in the amount of sludge supplied, but it can be said that the reaction was promoted because the amount of hydrogen generated increased.

  Next, the amount of cutting out was adjusted so that the mixing ratio of calcium hydroxide was 3.0 mol. However, since the amount of sludge supplied was increased in the same manner as described above, the ratio was low. However, although the concentration of coal dioxide was decreased by increasing the blending ratio, the amount of hydrogen generation was slightly decreased, and it is considered that there is a generation peak in this range. This is because the tendency of the fixed bed reactor used in the basic research was confirmed in a continuous test machine as well, so it is possible to connect the same results to the actual machine in the future. The proof was obtained. As a result, it is possible to design a practical plant based on the obtained blending ratio and the amount of hydrogen generation.

<Main conclusions from continuous tests>
In this embodiment, when the treatment temperature is 700 to 850 ° C. and the blending ratio is sludge: calcium hydroxide: nickel hydroxide = 1: 2.2: 0.45 (molar ratio), the hydrogen generation amount is 43.3 g / kg. Results were obtained. However, because of the small tester, it was greatly affected by disturbance (leakage air, etc.), and the nitrogen concentration increased and the hydrogen concentration decreased due to the inflow of outside air. For this reason, in the hydrogen production test apparatus P described above, introduction of a practical plant for producing high-efficiency and high-purity hydrogen by further improving the sealing performance of the entire apparatus P in order to suppress the influence of disturbance (continuous) Production of hydrogen production equipment by operation) becomes possible.

<Conclusion from study of introduction effect of practical plant>
Converting by-product hydrogen from conventional fossil fuels into hydrogen produced from sewage sludge, which is a local biomass resource, is important in terms of energy security, local energy independence and job creation. By the way, the sewage sludge collected from Hirosaki city has a solid content of 44.62% carbon, 6.69% hydrogen, 4.80% nitrogen, 30.10% oxygen, 0.49% sulfur, and water content. Since the molecular weight is close to the cellulose composition, such as 75.1%, the mixing ratio of calcium hydroxide and nickel hydroxide can be determined based on this.

  Here, in FIG. 8, production cost 1 = (calcium hydroxide and nickel hydroxide raw material purchase cost + input primary energy cost) / hydrogen recovery amount, production cost 2 = (calcium hydroxide and nickel hydroxide raw material purchase + input primary) Energy cost + 50t plant operation management costs, repair costs, burned ash disposal costs, depreciation costs (equal to 35 years)) / hydrogen recovery, energy balance = (higher heating value of hydrogen x hydrogen recovery) / input Primary energy, energy recovery rate = (higher heating value of hydrogen x hydrogen recovery amount) / (energy of organic components of sewage sludge + input primary energy), sewage sludge treatment cost 1 = (purchased calcium hydroxide and nickel hydroxide raw material) + Primary energy cost input) / Amount of sewage sludge to be treated, Sewage sludge treatment cost 2 = (Purchased calcium hydroxide and nickel hydroxide raw materials + Input primary energy cost) + 50t / day operation and management costs, repair costs and baked Sahai disposal costs, depreciation and amortization of plant (35 years equally)) / processing sewage sludge amount, it is.

P Hydrogen production test apparatus 1 First fixed supply hopper 2 Second fixed supply hopper 3 Third fixed supply hopper 4 Twin screw kneading screw (mixing means)
4a Pin screw part 5 Inlet seal 6 Nitrogen charging machine 7 External heating furnace (heating treatment means)
8 Hot-air generator 9 Condenser (Temperature reduction and dehumidification means)
DESCRIPTION OF SYMBOLS 10 Exhaust fan 11 Outlet seal 12 Adjustment pump 13 Circulating water tank 14 Carbonization furnace exhaust damper 15 Water ejector

Claims (3)

  A hydrogen production method characterized in that as a biomass resource, calcium hydroxide and nickel hydroxide are mixed in cellulose or sewage sludge and heated to produce hydrogen.   When the heat treatment temperature is 700 ° C. to 850 ° C., the mixing molar ratio of the biomass resource, calcium hydroxide, and nickel hydroxide is 1: (0.01 (not zero) to 3.0) :( 0. The hydrogen production method according to claim 1, wherein 01 (not zero) to 1.0).   As a biomass resource, mixing means for mixing calcium hydroxide and nickel hydroxide in cellulose and sewage sludge at a predetermined molar ratio, crushing and kneading, and supplying the pulverized and kneaded mixture to an external heating furnace Heat treatment means for exchanging heat and raising the temperature, and dehumidifying and dehumidifying means for reducing the temperature and dehumidifying various product gases generated by the heating reaction at the time of raising the temperature and introducing a part thereof into a continuous gas analyzer. A hydrogen production system characterized in that hydrogen is produced by a hydrogen production apparatus.

Images