EP1112461B1 - Method for operating a burner and burner arrangement - Google Patents

Description

The invention relates to a method for operating a burner, which a fuel quantity of a fuel over a Fuel supply line is supplied, the amount of fuel on the degree of opening of an actuator depending on a preset power of the burner is set. The invention also relates to a corresponding burner arrangement. Such a method and such an arrangement are out Document US-A-4,716,719 already known.

In the book "Die Gasturbine" by J. Kruschik, Springer-Verlag, Vienna 1960, 2nd edition, page 354 ff., Are different Control systems for burners of gas turbines described. Depending on The field of application of the gas turbine is very different Training in control systems. Common to the control systems, that depending on a preselected performance of the gas turbine a fuel supply to the burner is regulated. This happens e.g. speed-dependent via the regulation of a Actuator in a fuel supply line by means of a Centrifugal pendulum. In the example shown in Figure 359 Page 356 the amount of fuel supplied to the burner will depend from generated by the compressor of the gas turbine Air pressure regulated. In another example as shown in the illustration 361 on page 358 is the amount of fuel to be burned regulated with a flow / return nozzle. As from page 365 is the control system for the fuel supply an aircraft turbine is particularly demanding because here large temperature and pressure fluctuations in the outside air must become.

In "Dubbel, Taschenbuch für den Maschinenbau", edited by W. Baltz and KH Kütner, Springer-Verlag, 1990, 17th edition, chapter X15 6.4, it is stated that actuators for setting a mass flow of a medium depend on the density and the speed cause a drop in pressure in the medium. According to VDI / VDE guideline 2173, the flow of incompressible media is characterized by the k _v value (characteristic of the valve) experimentally determined for each arrangement as the volume flow of water (density ρ _o ) at temperatures from 5 to 30 ° C and a pressure drop Δp _V0 of 0.98 bar. Any pressure drops Δp _v and other densities ρ result in the volume flow V V = k V Δ p V ρ 0 / (Δ p v 0 ρ)

The dependence of the k _V value on the manipulated variable is the valve characteristic. K _V is related to the maximum value k _VS when the valve is fully open. The value k VS = V 0 Δ p V 0 ρ / (Δ p V ρ 0 ) with the maximum flow V ˙ ₀ z. B. specified by the valve manufacturer.

The object of the invention is to provide a method of operation of a burner with a pre-selected output related supply of fuel. Another object of the invention is the specification of a corresponding burner arrangement.

According to the invention, the object is directed to a method solved by a method for operating a burner, the a fuel amount of a fuel via a fuel supply line is supplied, the amount of fuel over the degree of opening of an actuator depending on a selected one Power of the burner is set and where the Degree of opening determined based on this performance and immediately is set.

The invention is based on the knowledge that one, usually carried out, iterative regulation of the supplied Amount of fuel depending on the preselected output too sluggish compared to suddenly changed operational conditions is. With such an iterative regulation, the Degree of opening gradually regulated so that the preselected Performance. In other control systems, the requested service e.g. through a generally very complex mechanical system directly converted into a manipulated variable, by which the degree of opening is determined. In such Systems usually results in a very limited Variability in response to changes Boundary conditions, because an implementation of the preselected Performance in the opening degree only with a preset, established mechanism takes place.

In particular, a burner for a gas turbine comes as the burner in question, but the invention is also e.g. for an internal combustion engine suitable for a vehicle. Fuel for the burner can e.g. B. be: petroleum, natural gas, diesel, gasoline or kerosene.

In contrast, the degree of opening is first in the invention calculated based on the selected power and then immediately set. This has the advantage that there is no iterative Regulation must be carried out. So there is a significant faster system response. So the system is very responsive much faster e.g. to external faults such as pump switching. There is also the advantage that the current Operating conditions better and more flexibly can, as the degree of opening adapts to the respective operating conditions is calculated. For example, are changes in the Temperature, density or type of fuel or an am Burner location variable pressure in a simple way for the Regulation of the amount of fuel to be supplied can be used. Compared to control systems with a direct, mechanical implementation results from the preselected power in the degree of opening a significantly increased flexibility with regard to changed boundary conditions.

The calorific value of the fuel is preferably determined and used to calculate the degree of opening. preferred dimensions becomes a mixture of at least two as fuel Fabrics used. To determine the amount of fuel required the calorific value of the fuel is used because this also determines a power release from the combustion. Such a determination of the calorific value is particularly important then an advantage if a fuel mixture is used possibly even with a time-variable composition. An oil-water mixture is preferably used as fuel used, the energy consumption for one Evaporation of the water determined during combustion and for Calculation of the degree of opening is used. Such Oil-water emulsion or dispersion is used to reduce Nitric oxide emissions used. By adding water the average combustion temperature is reduced. By the evaporation of the water becomes part of the energy of the Fuel consumes and therefore does not contribute to the desired Performance at.

The density of the fuel is preferably determined and Calculation of the degree of opening used. About the density of fuel is the mass flow of fuel through determines the fuel supply line. Especially when used of a fuel mixture is the determination of the density of fuel is an advantage.

A pressure loss in the fuel supply line is preferred determined and to calculate the degree of opening used. Such a loss of pressure causes the mass flow of fuel through the fuel supply line co-determined, so that this pressure loss advantageously is taken into account when calculating the degree of opening.

The burner preferably opens into a combustion chamber in which Combustion chamber pressure prevails, the combustion chamber pressure being measured and is used to calculate the degree of opening.

The pressure in the combustion chamber affects the amount of in fuel entering the combustion chamber. In particular in a gas turbine, there is a considerable amount in the combustion chamber higher pressure compared to the ambient pressure since the Combustion chamber supplied with combustion air from a compressor becomes.

A flow comparison value is preferably determined for the actuator, in which a fuel mass flow through the actuator results under the prevailing pressure conditions, which leads to selected burner output, the degree of opening being determined by means of a known relationship between the flow comparison value and the degree of opening. Such a flow comparison value is the k _V value given from the cited paperback for mechanical engineering.

The burner is preferred for optional operation with designed at least two different fuels. preferred dimensions is the burner both as a diffusion burner can also be operated as a premix burner. Preferably, the Burner designed for operation in a gas turbine, in particular for operation in a stationary gas turbine. Such a burner is e.g. both with petroleum and with Natural gas can be operated. It preferably has a central pilot burner which works as a diffusion burner, i.e. it there is no premixing of combustion air and fuel. The central pilot burner is from a main burner surround that works as a premix burner, i.e. combustion air and fuel are mixed first and then incinerated. The diffusion burner preferably has a flow / return nozzle, i.e. the fuel, especially petroleum, enters the nozzle via a flow channel on and partially out of the nozzle opening. The remaining one Part of the fuel is returned via a return line returned to a fuel collection container. The fed and the amount of fuel returned are each adjustable by its own actuator. The regulation the amount of fuel supplied is for such a system very complex. Flexible adjustment of the degree of opening depends on the respective operating conditions special advantage.

According to the invention is directed to a burner arrangement Object achieved by a burner arrangement with a burner, which a fuel amount of a fuel via a fuel supply line can be supplied, the amount of fuel depending on the degree of opening of an actuator selected power of the burner is adjustable, with a control device is connected to the actuator, in which Control unit the degree of opening depending on the power, the type of fuel and a pressure drop in the Fuel supply line can be determined and a corresponding signal is so transferable to the actuator that this degree of opening is set.

The advantages of such a burner arrangement result accordingly the above comments on the advantages of the method to operate a burner.

The invention is based on the drawing in one embodiment explained in more detail. The only figure shows schematically and not to scale a burner 1, which in a Gas turbine 2 is arranged. The gas turbine 2 points one behind the other switched a compressor 4, a combustion chamber 6 and a turbine 8. The burner 1 has a central one Diffusion burner 3 and the diffusion burner 3 in the form of an annular channel surrounding premix burner 5. The diffusion burner 3 comprises a flow channel 7 and a return line 9. The diffusion burner 3 opens out with a nozzle opening 11 into the combustion chamber 6. The premix burner 5 is connected via a Flow path 13 from the compressor 4 compressor air supplied. Compressor air is also, not shown here, fed to the diffusion burner 3. To the premix burner 5 leads a fuel supply line 15a. To the diffusion burner 3 guides a fuel supply line 15b. On The return line 9 is closed by a fuel return line 17 on. An actuator 19a is in the fuel supply line 15a and an actuator 19b into the fuel supply line 15b built-in. With the pistons 20a, 20b, a respective one is clearly shown Degree of opening O shown for the actuators 19a, 19b. An actuator 21 is in the fuel return line 17 built-in. It is also an opening degree with a piston 22 O illustrates for actuator 21. The actuator 19a is via a line 23a, the actuator 19b via a Line 23b and the actuator 21 via a line 25 with a control device 27 connected. In this control device 27 continues to lead a line 28 through which a desired Power L is entered for the gas turbine 2. The control device 27 is also connected via a line 29 connected to a pressure sensor 31 which is in the combustion chamber 6 is arranged. The fuel supply lines 15a and 15b are connected to a pump 39. Before the pump is 39 a mixer 37 switched. The mixer 37 is with a water tank 35 and an oil tank 33 connected. In the oil tank 33 The fuel return line 17 continues to open.

During operation of the gas turbine 2, oil B is released from the pump 39 the oil tank 33 conveyed into the mixer 37. Will continue Water H from the water tank 35 is fed into the mixer 37. Oil B and water H mix to form a fuel BRA. This is via the fuel supply lines 15a and 15b to the premix burner 5 and the diffusion burner 3. The fuel BH then burns in the combustion chamber 6. The resulting hot exhaust gas drives the turbine 8. ever after the desired output for the turbine 8 must more or less fuel BH can be supplied. It is also often desirable to have a variable water content H im Adjust fuel BH. With the variable water content both the calorific value of the BH fuel changes also the energy consumption for evaporation of the water H. The density of the BH fuel also changes. This variable sizes influence a release of performance during combustion so that the amount of fuel supplied BH to achieve the desired performance L accordingly must be regulated. In addition, e.g. sudden Pressure drops a very quick regulation of the supplied Make the amount of fuel necessary. These requirements the arrangement shown is just that the desired Power L is given to the control device 27, where from the physical boundary conditions the respective Degree of opening O of the actuators 19a, 19b and 21 calculated becomes. So there is no slow, iterative readjustment the amount of fuel supplied. In the calculation The degree of opening O flow the type and composition of the Fuel BH a so that you have a variable composition of the BH fuel. In detail the calculation of the degree of opening O e.g. as follows:

First the calorific value HW _{BH of} the fuel BH is determined using the mass flow m ˙ _H and the calorific value HW _{H of} the water H, the mass flow m ˙ _B and the calorific value HW _{B of} the heating oil B using the following formula: HW bra = m H · HW H + m B · HW B m H + m B

A negative calorific value HW _H for the water H takes into account the energy consumption for the evaporation of the water H.

In a second step, the density D _{BH of} the fuel is determined using the density D _{B of} the oil and the density D _{H of} the water using the following formula: D bra = ( m H + m B ) · D B · D H m H · D B + m B · D H

Furthermore, the pressure loss Δp _D in the diffusion burner 3 is determined from a characteristic value K which is specific to the diffusion burner 3 and is dependent on the incoming mass flow m ˙ _VL and the returning mass flow m ˙ _RL, using the following formula: Δ p D = K ( m VL m RL ) · m 2 VL · 1 D bra

The pipeline pressure drop Δp _R in the fuel supply lines 15a and 15b is determined using a k _V value k _VR specific for these lines using the following formula: Δ p R = m 2 VL · 1 D bra · 1 k 2 VR

With the aid of the combustion chamber pressure pB prevailing in the combustion chamber 6, the pressure pS to be set behind the actuators 19a, 19b is now determined from: pS = pB + Δ p D + Δ p R

The k _V value of the actuators 19a, 19b now results with the pressure pP behind the pump 39: k V = m VL D bra · ( pp - pS )

The desired degree of opening O is finally determined from the known relationship between the k _V value and degree of opening O. The respective degrees of opening O in the actuators 19a, 19b are set via signals SA, SB. A signal SC for the actuator 21 in the return line 17 takes place in the same way as the calculation of the signals SA and SB.

Claims (11)

1. Method of operating a burner (1), which is supplied with a quantity of a fuel (BH) by means of a fuel supply line (15), the fuel quantity being set by means of the degree of opening (O) of a setting element (19) as a function of a selected output (L) of the burner (1), characterized in that the calorific value of the fuel (BH) is determined, and that the degree of opening (O) is calculated using the selected output (L) and using the calorific value of the fuel (BH) and is set directly.
2. Method according to Claim 1, characterized in that a mixture of at least two materials (B, H) is used as the fuel (BH).
3. Method according to Claim 2, characterized in that an oil/water mixture is used as the fuel (BH), the energy consumption for any evaporation of the water (H) being determined during the combustion and being employed in the calculation of the degree of opening (O).
4. Method according to one of the preceding claims, in which the density of the fuel (BH) is determined and is employed in the calculation of the degree of opening (O).
5. Method according to one of the preceding claims, characterized in that a pressure loss Δp is determined in the fuel supply line (15) and is employed in the calculation of the degree of opening (O).
6. Method according to one of the preceding claims, characterized in that the burner (1) opens into a combustion chamber (6) in which a combustion chamber pressure (pB) is present, the combustion chamber pressure (pB) being measured and employed in the calculation of the degree of opening (O).
7. Method according to one of the preceding claims, characterized in that, for the setting element (19), a through-flow comparison value (k_V) is determined at which, for the pressure conditions present, there is a fuel mass flow through the setting element which leads to the selected output (L) of the burner (1), the through-flow comparison value (k_V) being employed in the calculation of the degree of opening (O).
8. Method according to one of the preceding claims, characterized in that the burner (1) is designed for optional operation with at least two different fuels (BH, G).
9. Method according to Claim 8, characterized in that the burner (1) can be operated both as a diffusion burner (3) and as a premixing burner (5).
10. Method according to one of the preceding claims, characterized in that the burner (1) is designed for operation in a gas turbine (2), in particular in a stationary gas turbine (2).
11. Burner arrangement having a burner (1), which can be supplied with a quantity of a fuel (BH) via a fuel supply line (15), it being possible to set the fuel quantity by means of the degree of opening (O) of a setting element (19) as a function of a selected output (L) of the burner (1), characterized in that a control device (27) is connected to the setting element (19), in which control device (27) a calculation of the degree of opening (O) can be carried out as a function of the selected output (L) and as a function of the calorific value of the fuel, it being possible to transmit a signal (S), for setting the degree of opening (O), from the control unit (27) to the setting element (19), whereby the degree of opening of the setting element is set directly according to the selected output and the calorific value of the fuel.

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