JPH01251558A - Phosphate type fuel cell power generating system - Google Patents

Abstract

PURPOSE:To accelerate the responsiveness of a power generating system when a load is quickly increased by providing a liquid fuel feeding device spraying and injecting liquid fuel into reformed gas. CONSTITUTION:This system has a fuel reformer 1, a high-temperature CO transformer 2, a low-temperature CO transformer 3, a phosphate type fuel cell main body 5, a liquid fuel storage tank 25, and a valve opening arithmetic unit 29. A liquid fuel feeding device is provided which is connected on the downstream side of the fuel reformer 1 of a fuel gas system and near the inlet of the CO transformer 2 and sprays and injects liquid fuel into reformed gas when the load 24 of the cell main body 5 is quickly increased. The liquid fuel injected into the reformed gas near the inlet of the CO transformer 2 when the load is quickly increased is immediately gasified due to the high-temperature reformed gas and constituting members, it is then reacted with the steam remaining in the reformed gas to generate hydrogen by the catalyst action in the CO transformer 2. The response of the power generating system to the quick increase of the load can be shortened to the inherent response of the cell main body.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the configuration of a power generation system using a phosphoric acid fuel cell.

[Conventional technology]

FIG. 4 shows a system and diagram of a conventional phosphoric acid fuel cell power generation system using natural gas, as disclosed in, for example, Japanese Patent Application Laid-Open No. 62-234871. In the figure, (1) is a fuel reformer,
(1') is the reforming reaction tube, (1b) is the reforming reaction tube (1
&), (2) is a high-temperature CO shift converter, C3) is a low-temperature aO shift converter, (4) is a steam/water separator, (5)
1 is a phosphate fuel cell main body, (5 &) is a fuel electrode in the phosphoric acid fuel cell main body (5), (5b) is an air electrode in the phosphoric acid fuel cell main body (5), (5 (1) is a cooling pipe in the phosphoric acid fuel cell main body (5), (6) is a steam separator, (7) is a pump that circulates cooling water in the steam separator (6), (8) ) is the air supply compressor, (9) is the turbine, GO is the auxiliary combustor, αυ is the flow rate control valve that adjusts the flow rate of natural gas, which is the raw material, shi is the flow rate control valve that adjusts the steam flow rate, ■ is natural gas α4 is a flow control valve that supplies air to the burner (1b).
), (To) is a flow rate adjustment valve for reformed gas, (To) is a flow rate adjustment valve for supplying air to the air electrode (5b), and α is for supplying air to the auxiliary combustor αO. The supplied flow rate control valve, (to) is a flow rate control valve that adjusts the circulating flow rate of cooling water, and (19-) to (19e) are heat exchangers supplied from the outside. Raw fuel such as natural gas is controlled by a flow rate control valve I to a predetermined flow rate depending on the load, and is supplied to the reforming reaction tube (1&) of the fuel reformer (1). The reformed gas with high hydrogen concentration discharged from the reforming reaction tube (la) is transferred to the heat exchanger (19a) →
High temperature CO transformer (2) → heat exchanger (19b) → low temperature CO
Transformer +3) → Heat exchanger (19o) → Heat exchanger (19a)
) where carbon monoxide is removed and the temperature is lowered to convert it into a fuel gas mainly composed of hydrogen, which is then dehydrated through a steam separator (4) and further into a heat exchanger (19o).
After passing through, the flow rate is adjusted by a flow rate control valve 09 and the fuel is supplied to the fuel electrode (5a) in the phosphoric acid fuel cell main body (5).

Gas containing hydrogen in an amount equivalent to the cell output is discharged from the fuel electrode (5a), sent to the auxiliary combustor α0, and used as fuel.

On the other hand, an oxidizing gas such as air is pressurized to a predetermined pressure by a compressor 8), and then adjusted to a predetermined flow rate by a flow rate control valve ■.
). Gas discharged after an amount of oxygen equivalent to the battery output is consumed at the air electrode (5b) is supplied to the auxiliary combustor CO as combustion air.

Fuel is supplied to the burner (1b) of the fuel reformer (1) by adjusting natural gas supplied from the outside to a predetermined flow rate using a flow rate control valve 0, and air is supplied from the compressor (8) through heat exchange. Vessel (1
After passing through 9e), the flow rate is adjusted by a flow rate control valve α4), and the fuel is supplied to the burner (1b) of the fuel reformer (1).

The gas discharged from the burner (1b) is transferred to the heat exchanger (19
After passing through e), it is supplied to the auxiliary combustor no. Pressurized air from the compressor (8) is also sent to the auxiliary combustor QQ through the flow control valve α.
The exhaust gas rotates the turbine (9) and drives the compressor (8). Cooling water is supplied to the cooling pipe (5C) in the phosphoric acid fuel cell body (5). The cooling water is sent from the steam separator (6) via the cooling water pump (7), and the cooling water discharged from the cooling pipe (50) is further passed through the heat exchangers (19a), (19b) and the flow rate control valve (to ) and back to the steam separator (6). In addition, the steam separated by the steam separator (6) is transferred to the reforming reaction tube (1) of the fuel reformer (1) via the flow rate control valve@
&) is mixed into the feed gas.

[Problem to be solved by the invention]

Conventional phosphoric acid fuel cell power generation systems are configured as described above, so when there is a sudden increase in the load on the phosphate fuel cell itself, the supply of fuel such as reformed natural gas is not in time and phosphoric acid is temporarily lost. Putting the salt fuel cell body into a fuel starvation state,
There are problems such as damage to the electrodes or the need to wait until the fuel supply is ready before increasing the load.

This invention was made to solve the above-mentioned problems, and it is a phosphoric acid fuel cell that can shorten the response of a phosphoric acid fuel cell power generation system to the unique response of the phosphoric acid fuel cell itself in response to a sudden increase in load. [Means for Solving the Problems] A phosphoric acid fuel cell power generation system according to the present invention is provided on the downstream side of a fuel reformer in a fuel gas system and on the downstream side of a CO transformer. It is equipped with a liquid fuel supply device that is connected near the inlet and sprays liquid fuel into the reformed gas when the load on the fuel cell main body increases rapidly.

[Effect]

In the phosphoric acid fuel cell power generation system of the present invention, when the load suddenly increases, the liquid ffi fuel, for example, a mist of low carbon number alcohol such as methanol, is directly injected into the reformed gas near the inlet of the CO shift converter in the fuel gas system. The reformed gas and components are immediately vaporized and reacted with the water vapor remaining in the reformed gas through the catalytic action in the CO shift converter to generate hydrogen, and the original fuel processing system in the power generation system is activated. The fuel shortage is compensated for until the reformed gas flow rate is increased in response.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In Fig. 1, the button indicates a storage tank for liquid fuel such as methanol, and the button indicates a mechanism for pressurized transport of liquid fuel such as methanol stored in the liquid fuel storage tank ω. (c) is a liquid fuel spray nozzle for directly injecting pressurized liquid fuel into the reformed gas near the inlet of the high-temperature CO shift converter (2), (c) is a control valve for liquid fuel such as methanol, and (c) is a control valve for liquid fuel such as methanol. Electrical load, @ is the fuel cell main body (5
) Load detection means for detecting the load of the DC ammeter (c), for example, a load increase rate calculation means for calculating the load increase rate from the load detected by the DC ammeter (c); A database that stores the upper limit of the load increase rate, etc. (in this example, the supply amount and supply time are also included) for the load calculated, of course, the current load and the load calculated by the DC ammeter and rate of change calculator (c). A supply determining means, that is, a comparator, which compares the load increase rate and the database information to determine the necessity and amount of liquid fuel supply. The valve opening degree calculator (to) that calculates the opening degree is a holder that holds the output of the valve opening degree calculator for a specified time from the information in the database (c). Other symbols in FIG. 1 are the same as those in FIG. 4 described in the explanation of the configuration of the prior art. ◇ Also, the rate of change calculator (c), comparator @, database handle, valve opening calculator, The holder (c) is realized by an 8-pit microprocessor, for example.
A fuel reformer that produces high-temperature reformed gas with a high hydrogen concentration (
In order to rapidly increase the supply flow rate of the reformed gas, which is the exit gas from the fuel reformer (1), it is necessary to optimize the thermal time constant of the fuel reformer (1). Production of reformed gas is usually a large endothermic reaction, and in order to rapidly increase the flow rate of produced gas, the amount of heat input to the fuel reformer (1) must be rapidly and effectively increased. Due to structural constraints, the actual response of the fuel reformer (1) is:
Battery-specific response (condition where fuel is constantly and ideally supplied)
It is more than 10 times slower than .

In this embodiment, the liquid fuel, such as a low carbon number alcohol such as methanol, which is directly injected into the reformed gas at the inlet of the high temperature OO shift converter (2), is immediately vaporized. After that, by the action of the shift catalyst in the high-temperature OO shift converter (2), the following reaction with water vapor contained in the reformed gas proceeds 〇0H30H→ CO +2H2 (1) CO + H20
→ ao2 + H2 (2) This reaction can compensate for the transient fuel shortage until the fuel reformer (1) follows suit, and instantly increases the load on the phosphoric acid fuel cell. It also becomes possible.

Next, the actual operation will be explained.

The output of the DC ammeter directly connected to the load of the phosphoric acid fuel cell main body (5) is input to the database balance, comparator, and rate of change calculator. Furthermore, the rate-of-change calculating unit □□□ calculates the rate of change of the phosphoric acid fuel cell current, and outputs the result to the database (c) and the comparator fin.

The comparator determines whether the load is increasing or decreasing based on the result of the rate of change calculator. If the load is increasing, the rate of increase determines whether the fuel supply It is determined whether or not the required limit value is exceeded, and the result and the current state are output to the valve opening degree calculator. The valve opening degree calculator determines the required valve opening degree and the opening holding time from the database name information according to the command from the comparator, and outputs it to the holder.

The holder operates the control valve (c) and the pump (pump) according to commands from the valve opening calculator.

FIG. 2 specifically shows the above control operation in a 70-chart. In the figure, the process started at 1CN T z R (3CO) first updates the memory at C3°C, and updates the current detection value 1 from the previous time. -1 to 1n-2 and edit the previous current detection value. is saved to Ln-1. Next, input the current value into 1n using the current value read function. In the rate of change (gradient) calculation (end), the rate of change Δ1n of the current value is calculated by, for example, a three-point approximation method. Database search from 1n-
yυ change rate upper limit Δ1Tt (total number of data in the database for 1-to-2), supply amount MDL (i-to-K)
% and supply time Tni (i-k to k) are extracted.

Next, the comparison function (to) compares the current rate of change Δ1n with the current rate of change ΔiTi based on the current value of 1U, and if Δ1! If l>ΔiTi, the valve opening calculation function (to) calculates the necessary increment ΔMY from the valve-specific function f based on the supply ffiMpi, and adds it to the current valve opening MV to obtain a new valve opening MY. . 1 more operation output (support)
Outputs the valve opening information M'7 and the supply time TDi, which is the database search result, from the holder ■ to the control valve and pump @, and ends the process with RETURN. Then, without any operation output, RK
Finish the process at TσRN@ In the above example, the liquid fuel injection point was installed in the reformed gas system piping near the inlet of the high-temperature CO shift converter (2). The one installed in the reformed gas system piping near the inlet of the low temperature CO shift converter (3) is shown in Figure 3, but as shown in Figure 3, the one installed in the reformed gas system piping near the inlet of the low temperature qO shift converter (3) You may.

In addition, the liquid fuel can be transferred to the steam/water separator (4) or the fuel cell body (5).
) may be considered to be injected near the inlet of the fuel electrode (5 &), but the temperature of these members is low, making it difficult for the liquid fuel to vaporize, and there is no catalyst to help convert the liquid fuel into hydrogen gas. Furthermore, there is a possibility that carbon monoxide, which is very inconvenient for the phosphoric acid fuel cell main body (5), remains unreacted.

In addition, although we used the DC current value of the phosphor-type fuel cell as the load detection certificate, a similar configuration is possible with the voltage value, and furthermore, if the load command is given in advance, the load command information can be directly transmitted to the valve opening calculator. - can be entered.

For reference, instead of spraying liquid fuel into fuel gas, it is also possible to inject fuel gas such as hydrogen stored in a cylinder, etc., but in this case, a large amount of hydrogen gas is required. This will take up space for storing cylinders, etc.

Furthermore, in the above embodiment, a case has been described in which the opening degree and opening time of valve (2) are controlled using control valve 0, which can control the opening degree. In this case, the same effect as in the above embodiment can be obtained by detecting the load at predetermined time intervals and controlling the M closing of the shutoff valve each time.

〔Effect of the invention〕

As described above, according to the present invention, the liquid fuel is connected to the downstream side of the fuel reformer in the fuel gas system and near the inlet of the CO transformer, and liquid fuel is injected into the reformed gas when the load on the fuel cell body increases. Since a liquid fuel supply device for spray injection is provided, it is possible to perform transient fuel gas compensation when the load suddenly increases, which has the effect of speeding up the responsiveness of the phosphoric acid fuel cell power generation system.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing a phosphoric acid fuel cell power generation system according to an embodiment of the present invention, FIG. 2 is a flowchart explaining the liquid fuel supply control operation of the system shown in FIG.
FIG. 4 is a system diagram showing a phosphoric acid fuel cell power generation system according to another embodiment of the present invention, and FIG. 4 is a system diagram showing a conventional phosphoric acid fuel cell power generation system. In the figure, (1)...Fuel reformer, (2)...High temperature aO shift converter% (3)...°Low temperature CO shift converter% (4)...
...Steam water separator, (5)...phosphoric acid fuel cell body,
(5m)... Fuel electrode, (5b)... Air electrode, (50
)...Cold MJ pipe, (8)...Air supply compressor, (
9) Turbine, αυ ~ flow control valve, (1
9&) ~ (19-)...Heat exchanger, ω...Liquid fuel storage tank, (c)...Liquid fuel pressurized transport mechanism, ■...Liquid fuel spray/slip, υ...Pressure Control valve (c)...
Load, @...DC ammeter, bit...rate of change calculator, of course...comparator, (c)...database, wire...valve opening calculator, (to)... It is a holder. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A fuel cell body that generates DC power by electrochemically reacting hydrogen in fuel gas and oxygen in oxidant gas;
A fuel reformer converts raw fuel into reformed gas with a high hydrogen concentration, and a CO shift converter removes carbon monoxide from the reformed gas to obtain fuel gas, and converts the fuel gas into the fuel cell main body. In a phosphoric acid fuel cell power generation system comprising a fuel gas system that supplies the oxidizing gas to the fuel cell body, and an oxidizing gas system that supplies the oxidizing gas to the fuel cell main body, A phosphoric acid fuel cell power generation system comprising: a liquid fuel supply device connected near an inlet of a CO transformer to spray and inject liquid fuel into reformed gas when the load on the fuel cell main body increases rapidly. (2) Load detection means for detecting the load on the fuel cell main body, load increase rate calculation means for calculating the load increase rate from the detected load, and the upper limit of the load increase rate for the load and load increase rate determined in advance. The phosphoric acid type fuel according to claim 1, further comprising: a supply determining means for determining whether or not to supply liquid fuel by comparing the fuel to the liquid fuel; and a control means for controlling the liquid fuel supply device based on the determination by the supply determining means. Fuel cell power generation system.