阅读说明：本技术 燃料重整装置和燃料重整方法 (Fuel reforming apparatus and fuel reforming method ) 是由 神原信志 三浦友规 田中裕弥 池田達也 于 2020-04-09 设计创作，主要内容包括：提供一种燃料重整装置,包括：氨罐(4)；重整器(5),用于重整氨并产生氢含量至少为99％的高浓度氢气；混合罐(7),用于混合氨和氢以进行临时储存；以及控制装置(10),用于控制供应至混合罐(7)的氨和高浓度氢气的各自的供应量。控制装置(10)基于等式(1)计算混合气体相对于基准燃料的燃烧率系数C。等式(1)：S-(0)＝S-(H)×C+S-(A)×(1-C)。在等式(1)中,S-(0)为基准燃料的燃烧率,S-(H)为氢的燃烧率,S-(A)为氨的燃烧率,C为混合气体的燃烧率系数。此外,基于等式(2),控制装置(10)确定供应至混合罐的氨和氢的体积分数。等式(2)：C＝1-exp(-A×M～(B))。在等式(2)中,M为混合气体中氢的体积分数,且A、B为常数。(Provided is a fuel reforming apparatus including: an ammonia tank (4); a reformer (5) for reforming ammonia and producing a high-concentration hydrogen gas having a hydrogen content of at least 99%; a mixing tank (7) for mixing ammonia and hydrogen for temporary storage; and a control device (10) forThe respective supply amounts of ammonia and high-concentration hydrogen gas supplied to the mixing tank (7) are controlled. The control device (10) calculates a combustion rate coefficient C of the mixed gas with respect to the reference fuel based on equation (1). Equation (1): s 0 ＝S H ×C+S A X (1-C). In equation (1), S 0 As a combustion rate of the reference fuel, S H Is the combustion rate of hydrogen, S A The combustion rate of ammonia and the combustion rate coefficient of the mixed gas are shown as C. Further, based on equation (2), the control device (10) determines the volume fractions of ammonia and hydrogen supplied to the mixing tank. Equation (2): c1-exp (-A × M) B ). In equation (2), M is the volume fraction of hydrogen in the mixed gas, and A, B is a constant.)

1. A fuel reforming apparatus for supplying a fuel gas containing ammonia and hydrogen to a combustion apparatus, the fuel reforming apparatus comprising:

an ammonia tank;

a reformer configured to reform ammonia and generate a high-concentration hydrogen gas having a hydrogen content of 99% or more;

a mixing tank configured to temporarily store a mixed gas of the mixed ammonia and the high-concentration hydrogen gas and supply the mixed gas as a fuel gas to the combustion apparatus; and

control means configured to control respective supply amounts of ammonia and the high-concentration hydrogen gas supplied to the mixing tank, and an amount of mixed gas supplied to the combustion means,

wherein the control device stores combustion rates of a reference fuel, hydrogen, and ammonia used in the combustion device, and calculates a combustion rate coefficient C of the mixed gas with respect to the reference fuel based on equation (1),

[ mathematical formula 1]

Equation (1): s₀＝S_H×C+S_A×(1-C)

Wherein S is₀Is the combustion rate, S, of the reference fuel_HIs the combustion rate of hydrogen, S_AThe combustion rate of ammonia, C the combustion rate coefficient of the mixed gas,

further, based on equation (2), the control means determines the volume fractions of ammonia and hydrogen supplied to the mixing tank,

[ mathematical formula 2]

Equation (2): c1-exp (-A × M)^B)

Where M is the volume fraction of hydrogen in the mixed gas and A, B is a constant.

2. The fuel reforming apparatus according to claim 1, wherein the control means further stores high heating values of the reference fuel, hydrogen, and ammonia used in the combustion means, and determines the flow rate fraction of the mixed gas with respect to the supply amount of the reference fuel according to equations (3) and (4) based on a ratio of the high heating value of the mixed gas with respect to the high heating value of the reference fuel,

[ mathematical formula 3]

Equation (3): h_m＝H_H×M+H_A×(1-M)

Equation (4): w_m＝H_m/H₀

Wherein H_mIs the high calorific value, H, of the mixed gas_HBeing a high heating value of hydrogen, H_ABeing high calorific value of ammonia, H₀Is the high calorific value of the reference fuel, and W_mIs the weight flow rate fraction of the mixed gas relative to the reference fuel,

further, the control means receives a fuel request rate of a reference fuel from the combustion means, and may determine a supply amount of the mixture gas to be supplied from the mixing tank to the combustion means based on equation (5) and equation (6),

[ mathematical formula 4]

Equation (5): m is_w＝2×M+17×(1-M)

Equation (6): f_m＝(W₀×W_m×1000)/m_w×22.4

Wherein m is_wIs the molecular weight, W, of the mixed fuel₀Is the fuel request rate of the reference fuel requested by the combustion device, and F_mIs the supply amount of the mixed gas to the combustion device.

3. The fuel reforming apparatus according to claim 1, wherein the reformer comprises:

a plasma reaction vessel for decomposing ammonia and converting it into plasma;

a plasma generating power supply; and

a hydrogen separation membrane disposed inside the plasma reaction vessel, the hydrogen separation membrane separating hydrogen from the plasma of ammonia and delivering the hydrogen as high-concentration hydrogen gas to an outlet on the mixing tank side;

wherein the control means controls the voltage of the plasma generation power source and the flow rate of ammonia from the ammonia tank to control the amount of production of the high concentration hydrogen gas.

4. The fuel reformer of claim 1, further comprising:

an ammonia decomposition catalyst reactor that decomposes a part of ammonia to generate a low concentration hydrogen gas having a hydrogen content of 5% to 15%; and

a low-concentration hydrogen tank that temporarily stores the generated low-concentration hydrogen gas and supplies the low-concentration hydrogen gas to the mixing tank;

wherein the control device is based on equation M_H＝(100×M-H_2L)/(100-H_2L) Determining a volumetric mixing fraction M of the high-concentration hydrogen gas supplied by the reformer to the mixing tank_HWherein H is_2LIs the hydrogen concentration (volume percent, N-free) of the gas in the low concentration tank₂)。

5. The fuel reforming apparatus according to claim 4, wherein the control means controls:

a first valve that controls a supply amount of ammonia supplied from the ammonia tank to the reformer,

a second valve that controls a supply amount of ammonia supplied from the ammonia tank to the ammonia decomposition catalyst reactor,

a third valve that controls a supply amount of the low-concentration hydrogen gas supplied from the low-concentration hydrogen tank to the mixing tank,

a voltage of a high voltage power supply that supplies power to the reformer,

the amount of electric power supplied to the ammonia decomposition catalyst reactor, and

a supply amount of the mixed gas supplied to the combustion apparatus.

6. A fuel reforming method for supplying a fuel gas containing ammonia and hydrogen to a combustion apparatus, the fuel reforming method comprising:

a step of determining a mixed fraction of ammonia and hydrogen;

a step of reforming ammonia by a reformer to produce a high-concentration hydrogen gas having a hydrogen content of 99% or more;

a step of mixing ammonia with the high-concentration hydrogen gas to produce a mixed gas; and

a step of supplying the mixed gas to the combustion device;

wherein the step of determining the mixing fraction of ammonia and hydrogen comprises calculating a combustion rate coefficient C of the mixed gas with respect to a reference fuel used in the combustion apparatus according to equation (1) based on respective combustion rates of the reference fuel, hydrogen, and ammonia,

[ math figure 5]

Equation (1): s₀＝S_H×C+S_A×(1-C)

Wherein S is₀Is the combustion rate, S, of the reference fuel_HIs the combustion rate of hydrogen, S_AIs the combustion rate of ammonia, and C is the combustion rate coefficient of the mixed gas,

further, based on equation (2), determining a volume fraction of hydrogen supplied to the mixing tank,

[ mathematical formula 6]

Equation (2): c1-exp (-A × M)^B)

Wherein M is the volume fraction of hydrogen in the mixed gas, A and B are constants, and

the mixing ratio of ammonia to the high-concentration hydrogen gas is (1-M): M.

Technical Field

The present invention relates to a fuel reforming apparatus that generates hydrogen by decomposing ammonia and supplies a gas containing ammonia and hydrogen as a fuel, and a fuel reforming method using the fuel reforming apparatus.

Background

The use of hydrogen energy is sought in order to reduce carbon dioxide emissions. However, the production and transportation costs of hydrogen are still high, and hydrogen-fueled fuel cells are still more expensive to generate than other types of energy. These economic limitations constitute factors that hinder the spread of hydrogen energy.

In contrast, it is considered to use hydrogen as a fuel in a combustion apparatus such as a gas engine, a gas turbine, a diesel engine, or a gasoline engine, which is cheaper in power generation output than a fuel cell. However, since hydrogen has a very high maximum combustion rate and a high heat value, applying hydrogen alone or a mixture of hydrogen and air to a combustion apparatus causes many problems.

For example, when hydrogen is applied to an engine, the occurrence of backfiring can become a problem. Backfire is a phenomenon that mainly occurs in a reciprocating engine, in which hydrogen contacts high-temperature components of a combustion apparatus and ignites in a fuel intake step, exploding before being ignited by a spark plug. Patent document 1 discloses a technique of avoiding backfire, in which hydrogen and air are premixed in or outside a combustion chamber during low-output operation to produce a premixed air-fuel mixture, which is ignited and burned by a spark plug to obtain output power, and hydrogen is injected at high pressure into the ignited premixed air-fuel mixture and ignited and burned using the premixed air-fuel mixture as an ignition source to obtain output power. However, it is pointed out that when hydrogen is mixed with air in gaseous form in the intake step, the volumetric efficiency of the engine is reduced, resulting in a reduction in output power.

Therefore, attempts are being made to mix ammonia and hydrogen and combust the mixture for use as an energy source. Since ammonia has poor ignitability and the maximum combustion rate is 1/50 of hydrogen, the ignitability can be improved and the combustion rate can be adjusted by premixing hydrogen with ammonia and air in appropriate proportions. In addition, the energy efficiency can be maximized by adjusting the optimum mixing ratio of ammonia/hydrogen/air for the loads of the gas engine and the gas turbine, the diesel engine and the gasoline engine, and the like.

Patent document 2 discloses a technique for improving flexibility of combustion control in an engine system in which ammonia and hydrogen are combusted. The engine system of patent document 2 partially reforms ammonia gas by a fuel reformer to produce hydrogen gas, and separates ammonia and hydrogen by pressure liquefaction. Then, by injecting ammonia and hydrogen into the intake pipe with injectors connected to different paths and burning the ammonia and hydrogen, flexibility of control is improved. In patent document 2, ammonia gas supplied to the chamber of the reformer is reformed into ammonia gas and hydrogen gas by supplying microwaves from a power supply that generates electromagnetic waves to the chamber to discharge plasma. The proportion of ammonia to be reformed into hydrogen is controlled by controlling the power of the supplied microwaves.

Patent document 3 discloses an ammonia engine using hydrogen as a combustion improver. The ammonia engine of patent document 3 uses an ammonia cracking catalyst to crack ammonia to generate hydrogen for assisting combustion of ammonia. Since the ammonia cracking catalyst needs to be maintained at a temperature of 290 ℃ or higher, the ammonia engine of patent document 3 includes an ammonia oxidation device that promotes the reaction of ammonia with oxygen to generate heat.

Documents of the related art

Patent document

Patent document 1: japanese unexamined patent publication No. H7-133731

Patent document 2: japanese unexamined patent publication No. 2009-97421

Patent document 3: japanese unexamined patent publication No. 2010-121509

Disclosure of Invention

Problems to be solved by the invention

When supplying a gas containing ammonia and hydrogen as a fuel to a combustion apparatus, it is necessary to optimize the supply amount and the mixing ratio of ammonia and hydrogen according to the operating conditions of the combustion apparatus. However, with the conventional reformer, it is difficult to precisely manage the proportion of hydrogen generated from ammonia, which makes it difficult to optimize the fuel. It is particularly difficult to provide a fuel of optimum composition during start-up or low load operation of the combustion apparatus.

The present invention has been made in view of the above-described situation, and an object thereof is to provide a fuel reforming apparatus and a fuel reforming method capable of optimizing a mixing ratio and a supply amount of ammonia and hydrogen and supplying them as fuel to a combustion apparatus.

Means for solving the problems

The present invention relates to a fuel reforming apparatus that supplies a fuel gas containing ammonia and hydrogen to a combustion apparatus. The fuel reforming apparatus includes: an ammonia tank; a reformer configured to reform ammonia and generate a high-concentration hydrogen gas having a hydrogen content of 99% or more; a mixing tank configured to mix ammonia and hydrogen for temporary storage; and a control device configured to control respective supply amounts of ammonia and high-concentration hydrogen gas supplied to the mixing tank. The control device of the fuel reforming device according to the present invention stores the combustion rates of the reference fuel, hydrogen, and ammonia used in the combustion device, and calculates the combustion rate coefficient C of the mixed gas with respect to the reference fuel based on equation (1).

[ mathematical formula 1]

Equation (1): s₀＝S_H×C+S_A×(1-C)

Wherein S is₀As a combustion rate of the reference fuel, S_HIs the combustion rate of hydrogen, S_AThe combustion rate of ammonia and the combustion rate coefficient of the mixed gas are shown as C. Further, the control device of the fuel reforming device according to the present invention determines the volume fractions of ammonia and hydrogen supplied to the mixing tank based on equation (2).

[ mathematical formula 2]

Equation (2): c1-exp (-A × M)^B)

Where M is the volume fraction of hydrogen in the mixed gas and A, B is a constant.

The inventors found the relationship between the combustion rate coefficient C, which is the ratio of the combustion rate of the mixed gas with respect to the combustion rate of the reference fuel in the above equation (2), and the volume fraction M of hydrogen, and finally optimized the mixing ratio of the mixed gas. Further, the control device of the fuel reforming device according to the present invention stores the high calorific value of the reference fuel, hydrogen, and ammonia used in the combustion device, and determines the flow rate fraction of the mixed gas with respect to the supply amount of the reference fuel according to equations (3) and (4) based on the ratio of the high calorific value of the mixed gas to the high calorific value of the reference fuel.

[ mathematical formula 3]

Equation (3): h_m＝H_H×M+H_A×(1-M)

Equation (4): w_m＝H_m/H₀

Wherein H_mIs a high heating value of the mixed gas, H_HBeing a high heating value of hydrogen, H_ABeing high calorific value of ammonia, H₀Is a high calorific value of the reference fuel, and W_mIs the weight flow rate fraction of the mixed gas relative to the reference fuel.

The control means receives a fuel request rate of the reference fuel from the combustion means, and may determine a supply amount of the mixture gas to be supplied from the mixing tank to the combustion means based on equation (5) and equation (6).

[ mathematical formula 4]

Equation (5): m is_w＝2×M+17×(1-M)

Equation (6): f_m＝(W₀×W_m×1000)/m_w×22.4

Wherein m is_wIs the molecular weight, W, of the mixed fuel₀Is the fuel request rate of the reference fuel requested by the combustion device, and F_mIs the amount of the mixed gas supplied to the combustion device.

The reformer of the fuel reforming apparatus according to the present invention preferably includes: a plasma reaction vessel for decomposing ammonia and converting it into plasma; a plasma generating power supply; and a hydrogen separation membrane disposed inside the plasma reaction vessel, the hydrogen separation membrane separating hydrogen from the plasma of ammonia and delivering the hydrogen as high-concentration hydrogen gas to an outlet on the mixing tank side. The control device of the fuel reforming device according to the present invention can control the voltage of the plasma generation power source and the flow rate of ammonia from the ammonia tank to control the amount of high-concentration hydrogen gas produced.

The fuel reforming apparatus according to the present invention may further include: an ammonia decomposition catalyst reactor that decomposes a part of ammonia to generate a low concentration hydrogen gas having a hydrogen content of 5% to 15%; and a low-concentration hydrogen tank that temporarily stores the generated low-concentration hydrogen gas and supplies the low-concentration hydrogen gas to the mixing tank. Control apparatus of fuel reforming apparatus including ammonia decomposition catalyst reactor based on equation M_H＝(100×M-H_2L)/(100-H_2L) Determining a volumetric mixing fraction M of high-concentration hydrogen supplied to a mixing tank by a reformer_H. Wherein H_2LHydrogen concentration (volume percentage, N-free) of gas in low concentration tank₂) And M is the volume fraction of hydrogen in the mixed gas.

The control device of the fuel reforming device according to the present invention controls: a first valve for controlling the supply amount of ammonia supplied from the ammonia tank to the reformer, a second valve for controlling the supply amount of ammonia supplied from the ammonia tank to the ammonia decomposition catalyst reactor, a third valve for controlling the supply amount of low-concentration hydrogen gas supplied from the low-concentration hydrogen tank to the mixing tank, the voltage of the high-voltage power supply that supplies power to the reformer, the supply amount of power supplied to the ammonia decomposition catalyst reactor, and the supply amount of mixed gas supplied to the combustion device.

The present invention also provides a fuel reforming method of supplying a fuel gas containing ammonia and hydrogen to a combustion apparatus. The fuel reforming method according to the present invention includes: a step of determining a mixed fraction of ammonia and hydrogen; a step of reforming ammonia by a reformer to produce a high-concentration hydrogen gas having a hydrogen content of 99% or more; a step of mixing ammonia with high-concentration hydrogen gas to produce a mixed gas; and supplying the mixed gas to the combustion device. The step of determining the mixing fraction of ammonia and hydrogen according to the present invention includes calculating a combustion rate coefficient C of the mixed gas with respect to the reference fuel according to equation (1) based on the combustion rates of the reference fuel, hydrogen, and ammonia used in the combustion apparatus.

[ math figure 5]

Equation (1): s₀＝S_H×C+S_A×(1-C)

Wherein S is₀As a combustion rate of the reference fuel, S_HIs the combustion rate of hydrogen, S_AThe combustion rate of ammonia, and C is the combustion rate coefficient of the mixed gas. Further, the fuel reforming method according to the present invention determines the volume fraction of hydrogen supplied to the mixing tank based on equation (2).

[ mathematical formula 6]

Equation (2): c1-exp (-A × M)^B)

Wherein M is the volume fraction of hydrogen in the mixed gas, A and B are constants, and the mixing ratio of ammonia to high-concentration hydrogen gas is controlled to be (1-M): M.

Effects of the invention

The fuel reforming apparatus and the fuel reforming method of the present invention generate high-concentration hydrogen gas having a hydrogen content of 99% or more from ammonia and mix it with ammonia as fuel, and therefore, the mixing ratio of hydrogen and ammonia can be easily optimized. This makes it possible to easily optimize the combustion in the combustion device to be supplied.

The fuel reforming apparatus and the fuel reforming method of the present invention can contribute to reduction of NOx emissions during combustion, thereby enabling optimization of the combustion apparatus.

The fuel reforming apparatus and the fuel reforming method according to the present invention can perform highly accurate combustion extremely easily by quantifying and controlling the volume fraction of ammonia and hydrogen when mixed and the combustion rate coefficient of the mixed gas with respect to the reference fuel.

The fuel reforming apparatus of the present invention can maximize the fuel yield by using a combination of the high-concentration hydrogen gas generated by the reformer and the low-concentration hydrogen gas generated by the ammonia decomposition catalyst reactor, and thus can be applied to a large-sized combustion apparatus.

The fuel reforming apparatus and the fuel reforming method of the present invention can maximize the energy efficiency of gas engines and combustion apparatuses such as gas turbines, diesel engines and gasoline engines by adjusting the fuel to an optimum ammonia/hydrogen/air mixing ratio and supplying the fuel.

The fuel reforming apparatus and the fuel reforming method of the present invention can maximize the energy efficiency of the power generation load by adjusting the fuel to the optimum mixing ratio of ammonia/hydrogen/air and supplying the fuel.

Drawings

Fig. 1 is a block diagram schematically showing the configuration of a fuel reforming apparatus according to an embodiment of the present invention;

fig. 2 is a block diagram schematically showing the configuration of a second embodiment of the fuel reforming apparatus of the present invention;

fig. 3 shows an embodiment of a reformer preferably applied to the fuel reforming apparatus of the present invention; and

fig. 4 shows the relationship between the catalyst layer temperature and the ammonia decomposition rate of the ammonia decomposition catalyst reactor of the present invention.

Detailed Description

Fig. 1 schematically shows a fuel reforming apparatus 1 according to an embodiment of the present invention. The fuel reforming apparatus 1 supplies a mixed gas containing ammonia and hydrogen as a fuel to the combustion apparatus 2. The combustion apparatus 2 is connected to a load 3, and changes a combustion state in response to a request on the load 3 side.

The fuel reforming apparatus 1 includes an ammonia tank 4, a reformer 5, and a high-concentration hydrogen tank 6. The ammonia tank 4 is connected to the mixing tank 7 via an ammonia supply path 25 to supply ammonia. Similarly, the ammonia tank 4 is also connected to the reformer 5 via another ammonia supply path, and supplies ammonia to the reformer 5. A first valve 21 is provided in an ammonia supply path connecting the ammonia tank 4 and the reformer 5, thereby controlling the supply amount of ammonia. Similarly, a valve 22 is provided in a path connecting the ammonia tank 4 and the mixing tank 7, thereby controlling the supply amount of ammonia.

A preferred embodiment of the reformer 5 of the present invention is shown in fig. 3. The reformer 5 is a device including a plasma reaction vessel 52 for decomposing ammonia and converting it into plasma, a plasma generation power source 53, and a hydrogen separation membrane 55 defining the hydrogen outlet 54 side of the plasma reaction vessel 52. A ground electrode not shown in the drawing is disposed in contact with the outside of the plasma reaction vessel 52. A discharge space 56 is formed between the inner surface of the plasma reaction vessel 52 and the hydrogen separation membrane 55, and ammonia supplied from the ammonia tank 4 is introduced into the discharge space 56. When a high voltage is applied from the plasma generation power source 53 to the hydrogen separation membrane 55, dielectric barrier discharge occurs, and ammonia is converted into plasma. The hydrogen separation membrane 55 of the reformer 5 separates hydrogen only from ammonia that becomes plasma in the plasma reaction vessel 52, and delivers the hydrogen to the hydrogen outlet 54 side. By controlling the amount of ammonia supplied to the reformer 5 and the voltage of the plasma generation power source 53, the amount of hydrogen generation can be easily and quickly changed. The hydrogen gas introduced into the hydrogen outlet 54 will be high purity hydrogen gas having a purity of 99% or more.

Since the reformer 5 can immediately generate hydrogen in response to a request on the combustion apparatus side, the high concentration hydrogen tank 6 as a temporary storage of hydrogen is not an essential component. However, by providing the high-concentration hydrogen tank 6 on the route from the reformer 5 to the mixing tank 7, an excessive amount of hydrogen gas can be temporarily stored, and the reforming of ammonia can be performed more efficiently as a whole.

In the mixing tank 7, ammonia supplied from the ammonia tank 4, hydrogen supplied from the high concentration hydrogen tank 6, and air additionally supplied from the blower 8 are mixed to generate a premixed mixed gas, which is stored in the mixing tank 7. The appropriate composition ratio of the mixed gas is determined by the control device 10 based on the combustion rate and the high heat value requested by the combustion device 2, and is managed by controlling the supply amount of ammonia and the generation amount of hydrogen. The supply amount of the mixed gas to the combustion apparatus 2 is controlled by the control apparatus 10 in accordance with the characteristics and load of the combustion apparatus 2.

Fuel reforming performed by the control device 10 of the fuel reforming device 1 according to the present embodiment will be described. The control device 10 controls the supply amount of ammonia supplied from the ammonia tank 4 to the reformer 5 using a valve 21, and controls the supply amount of ammonia supplied from the ammonia tank 4 to the mixing tank 7 using a valve 22. The control device 10 further controls the power supply voltage supplied to the reformer 5 to control the amount of generation of the high concentration hydrogen. Finally, the control device 10 controls the supply amount of the mixture gas supplied from the mixing tank to the combustion device 2 by the operation of the valve 23.

Hereinafter, the fuel conventionally used by the combustion apparatus 2 is referred to as "reference fuel". Table 1 shows examples of maximum combustion rates and high heating values for standard reference fuels, ammonia, and hydrogen.

[ Table 1]

The control device 10 stores the maximum combustion rate and the high calorific value of the reference fuel, hydrogen, and ammonia, and calculates a combustion rate coefficient C of the mixed gas with respect to the reference fuel based on the following equation (1).

[ math figure 7]

Equation (1): s₀＝S_H×C+S_A×(1-C)

Wherein S is₀As a combustion rate (cm/S), S, of a reference fuel_HIs the combustion rate of hydrogen, and S_AThe combustion rate of ammonia. According to the example shown in Table 1, S_H346cm/S, the combustion rate of hydrogen, and S_AIs 8 cm/s. The control device 10 uses theseThe combustion rate coefficient C of the mixed gas is calculated by the equation.

Further, based on equation (2), the control device 10 determines the volume fractions of ammonia and hydrogen supplied to the mixing tank. Calculation of volume fraction the volume mixed fraction M of hydrogen is first determined using equation (2) below.

[ mathematical formula 8]

Equation (2): c1-exp (-A × M)^B)

Where a and B are constants, the most preferred values are a 6.0 and B3.5.

After determining the volume mixing fraction M of hydrogen, the volume mixing fraction of ammonia becomes 1-M.

After determining the mixing fraction of hydrogen and ammonia, the control device 10 supplies the hydrogen and ammonia of the determined volume fraction to the mixing tank 7 to be mixed by the on/off operation of the valve 22 and the valve 24.

Next, the control device 10 determines the flow rate of the mixed gas supplied to the combustion device 2. The control device 10 stores high heat values of the reference fuel, hydrogen, and ammonia in advance, and first determines the flow rate fraction W of the mixed gas with respect to the supply amount of the reference fuel using equations (3) and (4)_m. Equation (3) for determining the high heat value H of the gas mixture_m. In equation (3), H_HIs a high heating value of hydrogen, H_AIs the high calorific value of ammonia, and M is the volume mixing fraction of hydrogen.

[ mathematical formula 9]

Equation (3): h_m＝H_H×M+H_A×(1-M)

As shown in Table 1, the higher heating value of hydrogen was 141.8MJ/kg, and the higher heating value of ammonia was 22.5 MJ/kg. Therefore, equation (3) is expressed as follows.

[ mathematical formula 10]

Equation (3'): H_m＝141.8×M+22.5×(1-M)

Next, the control device 10 uses equation (4) to calculate the high calorific value H of the mixed gas_mHigh heating value H relative to reference fuel₀Determines the flow rate fraction W of the mixed gas relative to the reference fuel_m。

[ mathematical formula 11]

Equation (4): w_m＝H_m/H₀

Further, the control device 10 calculates the molecular weight m of the mixed fuel using equation (5)_w. In equation (5), the coefficient 2 of the mixing fraction M of hydrogen is the mass number of hydrogen, and the coefficient 17 of the mixing fraction (1-M) of ammonia is the mass number of ammonia.

[ mathematical formula 12]

Equation (5): m is_w＝2×M+17×(1-M)

Then, when the fuel request speed W of the reference fuel is inputted from the combustion device 2₀(kg/h), the controller 10 calculates the flow rate fraction W of the mixed gas calculated in equation (4)_mAnd molecular weight m of the mixed fuel_wInto equation (6) to determine the supply amount F of the mixture gas supplied from the mixing pot to the combustion apparatus 2_m(NL/h)。

[ mathematical formula 13]

Equation (6): f_m＝(W₀×W_m×1000)/m_w×22.4

By controlling the amounts of ammonia and hydrogen supplied to the mixing tank 7 at the flow rate (NL/h), the control device 10 can keep the mixing ratio of ammonia and hydrogen in the mixing tank 7 constant. Flow rate F of hydrogen supplied to the mixing tank 7_H2(NL/h) is controlled using the following equation (7). In addition, the flow rate F of ammonia supplied to the mixing tank 7_NH3(NL/h) is controlled using the following equation (8).

[ mathematical formula 14]

Equation (7): f_H2＝F_m×M

Equation (8): f_NH3＝F_m×(1-M)

Fig. 2 shows another embodiment of the fuel reforming device of the present invention. The fuel reforming device 30 further includes an ammonia decomposition catalyst reactor 31 and a low concentration hydrogen tank 32. The ammonia decomposition catalyst reactor 31 decomposes a part of the ammonia supplied from the ammonia tank 4 to generate low-concentration hydrogen gas having a hydrogen content of 5% to 15%, a nitrogen content of 1.7% to 5%, and an ammonia content of 80% to 93%, and delivers the low-concentration hydrogen gas to the low-concentration hydrogen tank 32.

In addition to controlling the reformer 5, a control device 10The ammonia decomposition catalyst reactor 31 is also controlled to control the composition and the amount of generated hydrogen gas at a low concentration. The ammonia decomposition catalyst reactor 31 can control the decomposition rate of ammonia by controlling the reaction temperature, as shown in fig. 4. The low-concentration hydrogen gas is preferably controlled to have a hydrogen content of 5% to 15% in view of easy control of the temperature of the ammonia decomposition catalyst reactor 31. The control device 10 controls the property of the low-concentration hydrogen gas by controlling the power supplied from the power source 33 of the ammonia decomposition catalyst reactor 31. Preference is given to using Ru/Al₂O₃As an ammonia decomposition catalyst.

In the fuel reforming device 30 according to the present embodiment, the low-concentration hydrogen gas supplied from the low-concentration hydrogen tank 32, the hydrogen supplied from the high-concentration hydrogen tank 6, and additionally the air supplied from the blower 8 are appropriately mixed in the mixing tank 7 to generate a mixed gas, and the mixed gas is stored in the mixing tank 7.

At this time, using the following equations (9) to (12), the control device 10 bases on the volume mixing fraction M of hydrogen that has been calculated and the flow rate F of hydrogen supplied to the mixing tank 7_H2(NL/h), the amounts of the low-concentration hydrogen gas and the high-concentration hydrogen gas supplied to the mixing tank 7 are determined. Using equation (9), the mixing fraction (based on volume) M of the high concentration hydrogen tank 6 can be calculated_H。

[ mathematical formula 15]

Equation (9): m_H＝(100×M-H_2L)/(100-H_2L)

Wherein H_2LIs the hydrogen concentration (volume percent, N free) of the gas in the low concentration tank₂)。

Next, using equation (10), the flow rate F of the high concentration hydrogen gas supplied to the mixing tank 7 can be determined_HT(NL/h)。

[ mathematical formula 16]

Equation (10): f_HT＝F_m×M_H

Using equation (11), the flow rate F of ammonia supplied to the mixing tank 7 can be determined_LT(NL/h)。

[ mathematical formula 17]

Equation (11): f_LT＝F_m’×(1-M_H)

Wherein, F_m' is a fuel supply ratio (NL/h, N-containing) of the mixed gas supplied to the combustion apparatus₂)。

Using equation (12), the fuel supply rate F of the mixed gas supplied to the combustion apparatus 2 can be determined_m' (NL/h, containing N)₂)。

[ mathematical formula 18]

Equation (12): f_m’＝F_m×100/(100-N_2L)

Wherein N is_2LIs the nitrogen concentration (volume percent) of the gas in the low concentration tank.

Examples

(example 1)

The present embodiment shows an embodiment in which the fuel reforming device 1 according to the present invention is applied to generate fuel for a combustion device in which the reference fuel is methane, the fuel supply rate is 1.0kg/h, and the power generation amount is 1000 Wh.

The control device 10 stores 43cm/s as the maximum combustion rate of methane, and also stores 346cm/s as the maximum combustion rate of hydrogen, and stores 8cm/s as the maximum combustion rate of ammonia. Based on these maximum combustion rates, the combustion rate coefficient C of the mixed gas calculated using equation (1) is 0.104. The combustion rate coefficient C was substituted into equation (2), and the volume fraction M of hydrogen in the mixed gas was calculated to obtain a volume fraction of 0.319. Thus, the volume fraction of ammonia was 0.681. The high-concentration hydrogen produced by the reformer 5 and ammonia from the ammonia tank are supplied to the mixing tank 7 and mixed. The high calorific value H of the mixed gas at that time was calculated based on equation (3)_mThe value was 141.8 × 0.319+22.5 × 0.681 ═ 60.6. At the same time, the reference gas methane has a high calorific value H₀It was 55.5. By applying these values to equation (4), the weight flow rate fraction W of the mixed gas with respect to the reference fuel_mThe calculation was 0.917. At the same time, the molecular weight m of the mixed gas_wIs 12.2, so the fuel supply rate F of the mixed gas can be determined by using equation (6)_mWas 28.0 NL/h. In addition, in order to make the fuel supply rate F_mThe supply amount of hydrogen supplied to the mixing tank was determined to be 8.9NL/h using equation (7) while maintaining 28.0 NL/h. Similarly, using equation (8) willThe supply amount of ammonia supplied to the mixing tank was determined to be 19.1 NL/h. The combustion apparatus 2 achieved the desired combustion by supplying the mixed gas controlled to the hydrogen-ammonia volume ratio of 0.319:0.681 by the control apparatus 10 at a rate of 28.0 NL/h.

(example 2)

Next, an example is shown in which the fuel reforming apparatus 30 according to the present invention is applied to the generation of fuel for the combustion apparatus as in example 1, wherein the reference fuel is methane, the fuel supply rate is W0 ═ 1.0kg/h, and the power generation amount is 1000 Wh. In the present embodiment, the hydrogen concentration H of the low-concentration hydrogen gas generated by the ammonia decomposition catalyst reactor 31_2LIt was 7.7 vol%.

The controller 10 stores the maximum combustion rates and high heat values of methane, hydrogen, and ammonia, as in example 1. Then, by using equations (1) to (6), the fueling rate F of the mixed gas is determined_m28.0NL/h and a mixed fraction of hydrogen of 0.319. Further, the control device 10 uses equation (9) to adjust the mixing fraction (volume basis) M of the high concentration hydrogen tank 6_HWas determined to be 0.262. Therefore, it is determined that the hydrogen supply amount from the high concentration hydrogen tank 6 to the mixing tank 7 is 7.3NL/h using equation (10).

In order to produce 7.3NL/h of hydrogen by the reformer 5 and supply the hydrogen to the mixing tank 7, the control device 10 supplies 24.2l/min of ammonia from the ammonia tank 4 to the reformer 5. Then, a voltage of 20kV was supplied to the reformer 5 to generate hydrogen. At this time, the hydrogen gas supplied from the reformer 5 to the high-concentration hydrogen tank 6 has a concentration of 99.999% and is almost pure hydrogen.

The control device 10 determines the supply amount of the low-concentration hydrogen gas supplied to the mixing tank 7 to be 2.12NL/h using equations (11) and (12). In order to generate hydrogen gas of low concentration, the control device 10 set the reaction temperature of the ammonia decomposition catalyst reactor to 250 ℃ and supplied with 19.3l/min of ammonia. At this time, the ammonia decomposition catalyst reactor 31 produced a gas composed of 7.5% of hydrogen, 90% of ammonia and 2.5% of nitrogen at a rate of 2.12 NL/h. Since the control device 10 supplied 7.3NL/h of hydrogen gas from the high concentration hydrogen tank 6 to the mixing tank while supplying 2.12NL/h of low concentration hydrogen gas from the low concentration hydrogen tank to the mixing tank, the gas in the mixing tank was maintained at 31.8% hydrogen, 66.4% ammonia, and 1.8% nitrogen. By supplying the gas from the mixing tank as fuel gas to the combustion apparatus 2 at a rate of 28.5l/min, the combustion apparatus 2 can maintain desired combustion.

(example 3)

One embodiment of the application of the fuel reformer 30 to produce fuel for a methane gas engine is shown. The control device 10 sets the temperature of the ammonia decomposition catalyst reactor to 250 ℃ to generate a low-concentration hydrogen mixed gas having an ammonia decomposition rate of 10%, and stores this gas in the low-concentration hydrogen tank 32. The composition of the produced low-concentration hydrogen mixed gas was 7.5% hydrogen, 90% ammonia, and 2.5% nitrogen. Next, the reformer 5 generates hydrogen gas having a hydrogen content of 99%, and stores this gas in the high-concentration hydrogen tank 6. Then, 73.8% of the low-concentration hydrogen gas and 26.2% of the high-concentration hydrogen gas were mixed and stored in the mixing tank 7. The maximum combustion rate of the mixed fuel is 43cm/s and is matched with the maximum combustion rate of methane. In addition, since the high calorific value of the mixed fuel is 61MJ/kg, which exceeds the high calorific value of methane of 55.5MJ/kg, the flow rate of the valve 23 is controlled such that the flow rate of the mixed fuel into the methane gas engine is multiplied by 0.92. This allows the combustion apparatus 2 to achieve the desired combustion.

Although the fuel reforming apparatus and the fuel reforming method according to the present invention have been described based on the above-described embodiments, the present invention according to the scope of the claims is not limited to these embodiments, and the configuration of the fuel reforming apparatus may be appropriately modified. For example, as described above, the high concentration hydrogen tank is not essential, and the high concentration hydrogen gas may be directly supplied to the mixing tank from the reformer. The control content of the control device may be changed every second in response to the combustion characteristics of the combustion device 2.

Description of the reference numerals

1,30 fuel reforming device

2 combustion apparatus

3 load

4 ammonia tank

5 reformer

6 high concentration hydrogen tank

7 mixing tank

8 blower

10 control device