The method of adjusting the distribution of air flow

 

(57) Abstract:

The method can be used in the engine, namely in combustion chambers of gas turbine engines. At maximum load the hydraulic resistance of the mixing chamber air-fuel mixture is reduced due to the supply of jet fuel to the air flow direction, and with a minimum of strain respectively increases due to the supply of jet fuel against the direction of air flow. The technical result is increased reliability of the method of adjusting the distribution of air flow in the combustion chamber. 4 Il. , 1 table.

The invention relates to the field of engine construction and can be used in combustion chambers of gas turbine engines.

A known method of regulating the distribution of air flow, in which the quantity of air entering the primary zone of the combustion chamber is regulated mode external fan connected to the power source, forcing air to the burner depending on the load of the gas turbine, with the aim of supporting all loads of the gas turbine of the mixture in the combustion zone provides low levels of emissions of harmful substances the e-fan works by forcing air into the primary combustion zone and low system reliability regulation, contains moving parts in the flow part of the combustion chamber.

A known method of regulating the distribution of air flow on the primary and secondary combustion chambers with variable geometry, in which the regulation is effected by the axial movement of the stabilizer, changing the flow area of the front of the device, depending on the load of the gas turbine engine [2].

The disadvantage of this method is the low reliability of the design because it requires the introduction of the Executive transmitting mechanism regulating effect (electrical or mechanical) to the stabilizer of the combustion chamber.

Closest to the invention is a method of regulating the distribution of air flow along the contours of the combustion chamber (primary combustion zone, the zone of mixing with the combustion products), in which regulation is carried out by changing a pass square channel pipeline to channel a portion of the compressed air leaving the compressor to the burner [3]. In the pipeline is installed valve that changes the flow area of the pipeline. In the run mode the valve is installed in the position of minimum opening and the minimum quantity of air is agrusti the amount of air entering the primary zone is increased by opening the valve. The control system regulates the opening of the valve depending on the temperature before the turbine and the load of the turbine, which support the specified range of ratios of excess air and temperature in the primary combustion zone. Controlling these parameters reach reduce emissions of carbon monoxide, oxides of nitrogen and unburned hydrocarbons by maintaining the composition of the fuel-air mixture in the combustion zone provides low levels of emissions of harmful substances.

The disadvantage of this method is the low reliability of the design since there are moving parts in the flow part of the combustion chamber.

The problem to which the invention is directed, is to increase the reliability of the method of adjusting the distribution of air flow in the combustion chamber by eliminating moving parts in the flow part of the combustion chamber.

This object is achieved in that in the method of regulating the distribution of air flow which consists in changing the hydraulic resistance of the air path of the front device, the combustion chamber depending on the load of the gas turbine in contrast to the known prototype p is by applying jets of fuel in the air flow direction, and with minimal strain respectively increases due to the supply of jet fuel against the direction of air flow. Thus the use of the described method allows to operate the burner in a narrow range of composition of the mixture in the combustion zone is regulated environmental requirements and ensures the reliability of the method of regulation.

In Fig. 1 shows the results of calculations and experimental data on emissions of the burner operating conditions HPA GTK-10I.

In Fig. 2 shows a diagram of a combustion chamber in which is described the way.

In Fig. 3 depicts a graph of a program controlling the flow of air in the working conditions HPA GTK-10I.

In Fig. 4 shows a diagram of the experimental setup.

The method is carried out in the combustion chamber, containing in the front of the device, one or more burners with preliminary preparation of the fuel-air mixture in the mixer which must contain two injector for supplying gaseous fuel with the United independent fuel systems, through a single injector, the fuel is fed in the direction of air flow, and black the systems by using a fuel injection valve, heating pipe with holes for supplying dilution air with the hydraulic resistance that would be when fuel is in the direction of the air flow at maximum mode operation of a gas turbine coefficient of excess air in the primary combustion zone corresponded to the lowest possible excess air coefficient. The fuel flow valve must meet the following requirement: it is necessary to increase the hydraulic resistance of the line supplying air-fuel mixture when the load of the gas turbine engine and its decrease with increasing load, and maximum load all fuel must be supplied in the direction of the air flow, and a gradual transition to the fuel against the forward air flow should be in the case of lowering of the load when the level of emission of carbon monoxide begins to exceed the regulated environmental requirements level.

An example of a specific application of the method.

Consider the combustion chamber of the pumping unit GPA GTK-10I.

Working conditions of the combustion chamber:

the temperature at the inlet into the combustion chamber (Tin) - 543 K

Amer combustion (P) - 0.7 MPa

In the serial the combustion chamber of the aggregate emission levels of nitrogen oxides exceed environmental standards (NOx= 232 mg/m315% O2), because used in this design concept fuel combustion in diffusion mode. Modernization of the combustion chamber is in the installation of burners with pre-mix fuel, for example, a burner from [4].

A burner with axial swirler and pre-mix fuel consists of two tubes one inside the other, in the annular channel of the supplied air, the inner tube is supplied with gaseous fuel mixed with air in the annular channel.

The fuel supply is carried out from the holes located along and against the direction of air flow and placed on pylons on the outer surface of the inner pipe, respectively.

Swirling the expanding fuel-air flow at the outlet of the burner creates a stable zone of reverse currents for a slice of the inner tube, which ensures the stability of the combustion of pre-mixed fuel air mixture of a poor composition.

The control system its required fuel flow along and against the direction of air flow in the burner devices, similar in design and used a regulated supply duty fuel into the combustion chamber with the preliminary preparation of the fuel-air mixture poor composition. The fuel system also includes two rows of fuel pylons for supplying gaseous fuel along and against the flow direction of air (Fig. 2).

The programme of work of the regulatory system for gas turbine plants HPA GTK-10I. When the total air excess factor from 3,74 to 5.2 is the supply of gaseous fuel in the direction of the air flow, when the total air excess factor from 5.2 to 5,57 part of the fuel is fed against the direction of flow, when the total air excess factor above 5,57 all the fuel is fed against the direction of flow.

Current analysis shows that the use of this method of controlling the flow of air in the zone of preliminary preparation of the mixture depending on the degree of load of the unit provides an opportunity to ensure that environmental requirements for emissions of CO and NOxon the modes from 60% to 100% of maximum load.

The concentration of nitrogen oxides does not exceed at > 1,5 (coefficient of excess air in the primary zone) levels, limited ACDs optimal distribution of air flow over the length of the combustion chamber at maximum load unit SCC-10I (Fig. 1., the flow in the combustion zone is 43% of the total air flow through the combustion chamber).

Taking into account features of the business cycle gas turbine unit (GTU) unit SCC-10, you can make that work, shoot from the free turbine (payload) equal to thermal effect combustion of the fuel depends on the fuel consumption, and hence inversely proportional To the maximum mode, the coefficient of excess air for the whole combustion chamber = 3,74, taking into account the fact that in the primary zone receives 43% of the air on the mode 65% of the maximum coefficient of excess air in the primary zone will be equal to = 2,451 and as shown in Fig. 1. levels of carbon monoxide emissions for this mode in the absence of regulatory systems will be inflated.

The calculation of the change of hydraulic resistance in the above-described method of controlling the amount of air entering the primary zone was based on the well-known method proposed by G. N. Abramovich [5].

The system of equations includes:

the mass conservation law in the form

G3= G1+ G2< / BR>
the law of conservation of energy

< / BR>
the law of conservation of momentum

G3w3+ p3F3= G1p- specific heat at constant pressure, T-temperature, w is the velocity, p is the pressure, F is the area of the orifice.

Using the known gas-dynamic functions q () z() and the speed ratio of the above equations can be reduced to the dimensionless form:

< / BR>
< / BR>
< / BR>
where

n = G2/G1;

< / BR>
R is the gas constant;

k is the adiabatic exponent, the index "*" corresponds to the locked thread.

From the resulting system of equations, knowing the parameters of the flow at the inlet in the mixing device, it is possible to determine the flow parameters at the exit of the mixer, including the loss of total pressure in the mixing device p*= p*1-p*3:

< / BR>
where the index p denotes the parameters in the primary zone, the index of the parameters of the secondary air flow, index options at the entrance to the combustion chamber, - density, - - hydraulic resistance, referred to the output of the square element.

The range of operation of the burner is defined below the minimum to the questions of nitrogen oxides and top - maximum air excess factorCRwhere else are the environmental requirements for emissions of carbon monoxide. The excess air coefficient is a function of the costs of air and gas in the burner device.

The results of the calculations for this system of equations at T1= 543 K, T2= 288 K= 6,p= 2, P= 0.7 MPa,PR u= 2,min= 1,45 shown in Fig. 3.

Experimental data for comparison with the calculations shown in the table. The constructive scheme of the experimental setup is shown in Fig. 4.

Thus the proposed method can increase the reliability of the method of adjusting the distribution of air flow.

The sources of information.

1. U.S. patent N 4992040, CL F 23 D 14/02, 1985.

2. Canelo P. M. the Toxicity of the CCD and the prospects for the use of hydrogen. Kiev, Nauk. Dumka, 1982, 140 S.

3. International application WO 94/00718, CL F 23 R 3/34, 3/36, F 23 D 17/00, F 23 D 14/26, 1990.

4. Russian Federation patent RU 2036383 C1, class F 23 D 14/02, 1995.

5. Abramovich, N. Applied gas dynamics. M., Nauka. CH. nat. Ed. - Mat. lit., 1991, 600 S.

The method of adjusting the distribution of air flow, which in change is t load of the gas turbine, characterized in that at maximum load the hydraulic resistance of the mixing chamber air-fuel mixture is reduced due to the supply of jet fuel to the air flow direction, and with a minimum of strain respectively increases due to the supply of jet fuel against the direction of air flow.

 

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