The method of preparation of the mixture of air and fuel and its combustion in the combustion chamber of teploenergostroi and device for its implementation

 

(57) Abstract:

Usage: in the heat to reduce the intensity of formation of nitrogen oxides, combustion of the fuel mixture. The essence of the invention: method of preparing a mixture of air and fuel and its combustion in the combustion chamber of teploenergostroi, including a preliminary mixing and combustion of the mixture when the coefficients of excess air more or less stekhiometricheskogo values in a mixing units create a homogenized mixture of air and gaseous fuel ratios of excess air, serve them on separate channels to the mouth of the burner, providing at the output of the channel averaged over the cross section of the flow ripple values of the coefficient of excess air pre-mixed parts of the mixture stirred between them and the components of the combusted mixture components, and then burn the mixture. In the device for implementing the method in some of the channels for supplying the components of the mixture in the combustion chamber at the entrance set the mixing nodes, which hosted sites for the degeneration of pulsations concentration in the mixture, the mixing units installed turbulizers elements 7 the second mixture, used in teploenergostantsij TPP, TPP, production-heating boilers, and other heating units, and aims to reduce emissions of oxides of nitrogen.

There is a method of preparing a mixture of air and fuel for combustion in the combustion chamber of teploenergostroi and device for its implementation.

The known method includes a preliminary mixing and combustion of the mixture when the coefficients of excess air greater than or less than the stoichiometric value.

A device for implementing this method contains the channels for supplying the components of the mixture in the combustion chamber.

However, the known method is impossible or very difficult to uniformly mix the fuel and air supplied to the burner.

The technical result that is achievable with the use of the invention is to reduce the pulsations of the concentration of the fuel combusted mixture by step training.

The technical result is achieved by creating in the mixing units homogenized mixture of air and gaseous fuel ratios of excess air that have values outside the limits of Flammability, served their Otaci values of the coefficient of excess air pre-mixed parts of the mixture stirred between them and the components of the combusted mixture components, and then burn the mixture, and the ripple factor values pre-mixed part of the mixture at the outlet of the channels is determined according to the following ratios:

< / BR>
where < - the instantaneous value of the coefficient of excess air at the point of the cross section of flow in the channel with the probability density distribution P();

- averaged over time, the value of the coefficient at the point of the cross flow;

- average expense ratio value.

In the device for implementing the method in some of the channels on the mixing units, which hosted sites for the degeneration of pulsations concentration in the mixture, the mixing units installed turbulizers elements.

In Fig.1 shows the proposed device; Fig. 2 - section A-A in Fig.1; Fig.3 - node I in Fig. 1.

The device comprises a reservoir 1, the mixing unit that includes the block to the gas feed holes 2, the site for mixing the gas jets with the air supplied through the channel 3, channel 4 on plot M-N, the hole 5 channel 6 and the turbulent element 7.

Of the collector 1, the gas is fed into the mixing unit, located between the planes M and P, air is supplied through the channel Alu 4 on the section M-N degenerate ripple concentration. Channel 6 through the opening 5 in the same area is served extra fuel, which is mixed with a previously prepared air-fuel mixture.

The method is based on the reduction of pulsations concentration of fuel combusted mixture by step training.

Perenesennosti gases in the mixture is estimated by the magnitude of the heterogeneity of the average concentrations and the level of fluctuations of the concentrations at the point of flow section. The concentration is determined by the ratio of the mass of the impurity (impurity - gas with less consumption) in the selected volume to the bulk of this volume.

Typically the mixture in a section of the flow is characterized by the magnitude of heterogeneity, defined by the formula

< / BR>
where is averaged over time, the concentration of impurities in the point section of the stream;

- average expenditure concentration of impurities, determined by the cost of mixed gases.

To assess the heterogeneity of the average concentrations is also another more obvious and easily measured in experiments, the value of

< / BR>
where the maximum and minimum values of the average concentration in the section.

It is possible and appropriate to characterize the mixture the size of a cat who's of the devices to withstand < 0,05.

More adequately characterize perenesennosti mixture value associated with the instantaneous concentrations.

If C is the instantaneous concentration of impurities in the cross-sectional point of the thread with the probability density distribution P(C) then

< / BR>
The variance of the instantaneous concentration at a point is defined as

< / BR>
Similarly, we can determine the average concentration for flow and pulsation concentration in cross section. It is easy to see that point, and in section

The relative ripple concentration at the point of the cross section of flow is determined by the value of

Moving from concentrations to the air excess factor , it can be shown that

< / BR>
and then the above formula can be represented in the form

< / BR>
where to put the indices corresponding to the indices in C.

Value as <C'>/C is a measure of the homogeneity of the mixture: = 0 corresponds to the mixture homogenized to the molecular level.

By thorough mixing of air and gaseous fuel, as you can see, you can significantly reduce the emissions of NOx. However, there is a serious problem: risk of ignition in the burner mixture in the breakthrough plateni, when mixture is not ignited. For natural gas at the temperature of 25oC lower flammable limit = 1.8 and and top = 0,65.

When > 1.8 and < 0,65 mixture explosion proof. This mixture can be mixed in a mixing node and to submit to the mouth of the burner and combustion additionally serve fuel, in particular mixed with air from the calculation that the zone of combustion was maintained for a total value of > 1, 2 or < a 0.9. Should probably go from mixtures with > 1.8 and add to the desired fuel (in pure form or in mixtures in air, as well as possible additional supply of liquid fuel, such as fuel oil), because the amount of this additional fuel mass is small. If pre-prepared mixture of 0.65, then the zone of combustion will need to submit the air or mixture of air and fuel with > 1 in large quantities, which will cause difficulties in ensuring good mixing of the primary and secondary flows before burning.

1. The method of preparation of the mixture of air and fuel and its combustion in the combustion chamber of teploenergostroi, including a preliminary mixing and combustion of the mixture when the coefficients of excess air greater than or men is by a mixture of air and gaseous fuel ratios of excess air, having values outside the limits of Flammability, serve them on separate channels to the mouth of the burner, providing at the output of the channel averaged over the cross section of the flow ripple values of the coefficient of excess air pre-mixed parts of the mixture stirred between them and the components of the combusted mixture components, and then burn the mixture, and the ripple factor values pre-mixed part of the mixture at the outlet of the channels is determined according to the following ratios:

< / BR>
< / BR>
where <>2- dispersion that characterizes the dispersion of values of the coefficient of excess air;

- the instantaneous value of the coefficient of excess air at the point of the cross section of flow in the channel with the probability density distribution P () ;

- averaged over time, the value of the coefficient at the point of the cross flow;

- average expense ratio value.

2. Device for preparing a mixture of air and fuel and its combustion in the combustion chamber of teploenergostroi containing channels for feeding the components of the mixture in the combustion chamber, characterized in that at least some of the channels on the mixing units, which hosted sites for degeneration is the Plac CE turbulizers elements.

 

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