JPS58166675A - Combustion control method of reformer - Google Patents

Abstract

PURPOSE:To automatically perform the optimum control by finding supply and flow out energy to a reformer based on measured values of flow rate and temperature of gas, and separating the amounts of operation loss and of ordinary loss, to compensate the variation of operating conditions. CONSTITUTION:Fuel is supplied to an anode room 12 of a fuel cell 10 from a reaction part 22 of a reformer 20. Unreacting fuel 80, unreacting air 100 from a cathode room 11, air 110 from a compressor, and fuel gas-for-combustion 40 are supplied to a combustion room 21 of the reformer 20 to operate. A signal proportional to flow rate and temperature of flow in and flow out materials to and from the reformer 20 and to a load is inputted to a control apparatus 130. The heat in the reformer 20 is separated to the amount of operating loss proportional to operating conditions and the amount of ordinary loss which is not varied by operating conditions and calculated, and a control valve 43 is controlled so as to correct the amount of operating loss when operating conditions were varied. Therefore, control of fuel flow rate corresponding to the change of operating conditions is automated.

Description

[Detailed description of the invention] The present invention relates to a combustion control method for a reformer.

Method 1 to improve the power generation efficiency of a fuel cell power generation system by 4 degrees
One method is to control the fuel flow rate of the fuel reformer. As a specific method, a method has been proposed (% Publication No. 50-15058) in which the flow of reforming fuel and combustion fuel to the reformer is controlled by the cell current and reformer temperature. This method uses feedforward control to improve followability when the battery current changes, and to keep the reformer temperature constant during steady state.

In devices such as fuel reformers that operate at high temperatures and involve exothermic and endothermic reactions, the thermal efficiency differs depending on the load level, so conventional methods often do not control the devices optimally. As a result, the temperature of the reformer changes significantly, causing problems such as more fuel than necessary being supplied and a temporary drop in thermal efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control method that solves all of the problems of the prior art described above and automatically adjusts the amount of fuel supplied to a reformer according to the load.

Next, the points of the present invention will be described.

Since the fuel reformer is operated at high temperature, high temperature 1. *Fuel is burned to maintain energy, but the energy generated is lost in three main ways:

(1) Used as energy for reforming.

(2) Loss from high-temperature equipment to energy, auxiliary equipment, and atmospheric pressure (steady-state loss).

(3) Reformed gas and combustion gas carry away (operating loss).

In (2) above, if the reformer is operating, there is almost no difference depending on the operating conditions, and a constant amount of heat is always lost, but in (1) and (3), there is a marked difference depending on the operating conditions. come.

In the present invention, heat generated during fuel reforming is separated into operating loss proportional to operating conditions and steady loss that does not change, and when operating conditions change, the former operating loss is corrected. Adjust the fuel flow rate tIIl to .

A preferred embodiment of the present invention will be described below with reference to FIG. - The fuel cell 10 has a cathode chamber 11 and an anode chamber 12.
has an electrolyte 15t- between a pair of electrodes 13 and 140.
This is what was placed. The fuel reformer 20 has a combustion chamber 21 and a reaction section 22 inside.

The reforming fuel gas is supplied through a 50t pipe having a flowmeter 51t.
Flows into the reaction section 22 through the reactor. υ reforming steam is supplied to the reaction section 22 through a pipe 60 having a flow needle 61i. The fuel gas decomposed in the reaction section 22 is guided into the anode well 12 through a pipe 70 having a flow rate 171. Inside the cathode chamber 11, air, which is an oxidizing gas discharged from the pressure #1 IlfIA (not shown), flows through the pipes 110 and 9.
By supplying air to the cathode chamber 11 and fuel gas to the anode chamber 12, an electrochemical reaction occurs between the electrodes 13 and 14 and the electrolyte 15, and a voltage is generated between each electrode. The energy is
Taken out by circuit 31 and led to external negative 0830.

Combustion fuel gas passes through 40t of piping to the anode chamber 12.
The unreacted fuel gas in the cathode chamber 11 passes through pipe #80, and the unreacted air in the cathode chamber 11 passes through pipe V100' to the compressor (
The combustion gases discharged from the combustion chambers (not shown) pass through the distribution chambers 110 and are respectively supplied to the combustion chambers 21 of the fuel reformer 2G. The supplied fuel gas and unreacted fuel gas are combusted within the combustion chamber 21. Thermal energy generated by this combustion is used to reform the reforming fuel gas in the reaction section 22. The remaining thermal energy is transferred to the combustion gas and the piping 12.
Ejected from 0. This combustion gas is sent to a gas turbine (not shown) for driving the compressor.

The amount of combustion fuel gas supplied into the combustion chamber 21 is:
It is controlled by the 111 section valve 4a.

Flow needles 41.81, 101, 111 and 121 are provided in piping 40, 80, 100, 110 and 120. 52.62.72.82, 102°112 and 1
22 is piping 50,6/0.7G.

80.100, 110, and 120 are temperature needles that detect @Ct of flowing gas.

The 71tlj control device 130 inputs signals proportional to the flow rate and temperature of the inflow to the fuel reformer 20 and the outflow from the fuel reformer 20, as well as the load, and based on these signals, the TE! 14j
lrl valve 43t-control. Control device 13GtC! This will be explained based on the control sound, second garden, and Inx diagram.

FIG. 2 is an operation flow diagram of the control device 130. Since the load is constant during steady operation, the output of step 131 is no, and the amount of input heat during steady operation is calculated in step 132.

Qν舅P6・(q4 +Cp*・TI) +Fl・C
9a -T舊+P, ・ape ・Ts +Ps
・ (Q* +CPa ・T Insect) + F1@ ・
Cri+e ・T111+P11 ・CPtt+Ttt
= ”(1) Here, Q is the input heat amount (kJ/I)F4
is the flow of combustion fuel gas t (mot/I)q4 is the combustion heat of combustion fuel gas (kJ/no/,)CI)4
n Specific heat of fuel for fida, t, (kJ/m0t
-K)T1 is the temperature of the combustion fuel gas (K)F
s is the reforming fuel gas flow i1 (mot/1)F
6 is the reforming steam fit (mot/I)c
p- is the specific heat of reforming steam (kJ/mo/, -K)
T・ is the temperature of reforming steam (K), Fi is the flow rate of unreacted fuel gas (mot/8), q・ is the heat of combustion of unreacted fuel gas (kJ/mo/,) Cp, W'
i Unreacted fuel gas XO ratio (kJ/m0j-K)T, is the temperature of unreacted fuel gas, Specific heat (kJ/m0L-K) Tll is the temperature of unreacted air IC (K) Flt is the combustion g! Flow rate of 9 qi (mOj/I
) CRt is the specific heat of combustion air (kJ/moj −
K) Tll is the temperature (K) of the combustion air.

As shown in Fig. 3, one person's heat QyFi is consumed by the steady loss Qt and the operating loss Qo, and Qo is further consumed by the reforming heat Qm and the heat carried away by the outflow gas Q! It can be divided into Q, and 0! is calculated in step 133.

Q genus=F, ・qR,・・・・・・・・・・・・・・・
...12) Qr =Fv・cp,・Ty+Ft*-C
P+t,・Tit・・・・・・・・・・・・(3) Here, Q is the amount of heat required for reforming (kJ/5)q−
is the heat of reforming (kJ/mot) Qr is the amount of heat carried away by the outflow gas (kJ/ladder F1 is the reaction part 2
The flow rate (moz/yield) of the fuel gas flowing out from the reaction section 22, Cp, is the specific heat (k) of the fuel gas flowing out from the reaction section 22.
J/mot-K) T is the flow rate of the fuel gas flowing out from the reaction section 22 (K) Fll is the flow rate of the combustion gas (mot/5)c
pll is the specific heat of combustion gas (kJ/m0t-K)
'I'll is the temperature of combustion gas (K)
It is.

The steady loss Q7 can be determined from the difference between the input heat amount Qv and the operating loss QoO, and is calculated in step 134.

Qt:=Qv Qm Qt...
・・・・・・・・・・・・・・・(4) Next, the fuel cell 10
When the load changes by a factor of 9 (4>C), the output of the load signal 32 step 131 becomes y@S, and the amount of change in heating amount is calculated in step 135. In this case, normally a control device supplies fuel gas and air to the fuel cell lO in proportion to the load, a control device operates the t-operation, and the amount of change in the amount of heat required for reforming and the amount of heat removed by the outflow gas is expressed as follows: Become.

jQ Otori 3Q Lice ・ (j-1) ・kR・1111
+11@・・・・・・・・・・・・(5)ノQ! Turtle Q!
・(j-1) ・kT ・・・・・・・・・・・・・
・・・・・・(6) Change in amount of heat required for modification of l Q m Fi (kJ/I
)lQ! is the change in the amount of heat carried away by the outflow gas (kJ/I), kR is the correction coefficient (usually 1G), and kT is the correction coefficient (usually 1.0).

The amount of heating is Qr plus 4Gm and IQv, which is calculated in step 136 and output signal 1 from the control device.
37 (Fig. 1), combustion fuel gas flow rate control device 4
2 inputs the output signal 1377 to obtain the combustion fuel gas flow rate tg*. That is, in the present invention, control is performed so that only the amount of heat that changes according to the load change is corrected by t.

Although the invention has been described in terms of specific embodiments thereof, it is understood that the invention is not limited to the embodiments described and that various applications are possible within the scope of the invention. It will be clear to those skilled in the art.

For example, the signal 32 to the controller 130 can be electrically powered instead of current to achieve the same effect.

In Figure 9, #I1, the entire gas flow rate at the inlet and outlet of the reformer is measured, but it is possible to specifically calculate the flow rate by omitting the flow rate measurement of the outlet gas. Furthermore, the flow rate of unreacted fuel is also difficult to calculate based on the battery current.

According to the present invention, there are the following effects.

(1) The required combustion fuel flow rate t can be automatically adjusted in response to the driving conditions f.

(2) Due to the effect of (1) above, temperature changes in the reformer are reduced, and more fuel than necessary can be prevented.

(3) By automating the operation, the labor of the operator can be reduced.

[Brief explanation of drawings]

Figure 1111 is an example of a fuel cell power generation system to which the device @ is applied.
Figure 3 is a diagram showing the heat balance diagram of the present invention.

Claims (1)

[Claims] 1. A combustion chamber to which combustion fuel gas, unreacted fuel gas, unreacted oxidizing gas, and combustion air are supplied to the fuel cell and exhaust combustion gas, and a combustion chamber to which reforming fuel gas is supplied and reformed. In a method for controlling a reformer 06 hook having a reaction section and t for emitting fuel gas t#, each of said gases 011
and determine the energy supplied to the reaction section and the combustion chamber and the energy flowing out from the reaction section and the combustion chamber based on these measured values,
Since these energies change with operation, they are divided into a four-wheel rotation loss amount and a steady loss amount that does not change with operation, and when the operating conditions change, fuel gas for combustion is supplied to compensate for the above-mentioned operating loss amount. A combustion control method for a reformer characterized by controlling the amount.