Master's work

Master's work theme: "Optimization of the thermal and ecological conditions of a boiler ДЕ-25-14 ГМ"

Nowadays fuel and energy complex of Ukraine is in the crisis. In the following 20 years the national economy will remain operating with energy shortage. Ukraine provides only 45% of necessary annual consumption, which accounts for 150-170 mil. tons of coal fuel and it requires constant imports of fuel and energy resources. That is why it is important to use secondary energy resources - artificial gas fuel, which is generated while technological processing of solid fuel.

The boiler ДЕ-25-14 ГМ, heated by by-product of coking - coke oven gas, was chosen to be the subject of our investigation.

The main goal is to optimize the thermal conditions of operating of a boiler, heated by coke oven gas; investigate the impact of coefficient of air excess on economy of work and emission of harmful components of products of combustion after incineration of the coke oven gas.

1. Building up the mathematical pattern for optimization of thermal conditions of the boiler.

In order to optimize the thermal conditions the method of central composition orthogonal planning of full factorial experiment was used.

Mathematical statistics upon the solution of extremal tasks use the active experiments, which are hold according to deliberately-elaborated plan. On the results of active experiment the model of boiler was built.

The ecological and heating tests became the initial data for building the model of boiler.

For building of the model the following has been done: choice of factors and response, fields of shift of each factor; choice of a type of equation; holding the experiment, evaluation of its outcomes; defining the coefficients of equation; determining their importance; check-up of the correspondence of the model received to the subject under investigation.

The equation of regression looks like:

The factors of receiving of mathematical model were: consumption of coke oven gas (Х1), coefficient of air excess (Х2), the temperature of heating of nourishing water (Х3) and the temperature of outgoing products of combustion (Х4); response is the - productivity of the boiler. Y=f(X1;X2;X3;X4). For each point of factorial space the 4 values of Y response were determined. The matrix-plan of full factorial experiment was built.

The following check-ups have been held: homogeneity of dimensions in all points of the plan; per-line dispersions and homogeneity of the values .

The values of the coefficients of chosen model were calculated.

With the help of Student's criterion the check-up of meaning of the coefficients of regression equations, during which insignificant coefficients were put aside, was carried out. Thus, the meaningful coefficients are b0, b1, b2, b3, b4, b7.

Thus the final equation of regression has the following view:

Correspondence of the model to the experimental data was checked with the help of Fisher's criterion. While there is 5% level of meaningfulness, the design value of Fisher's criterion is less than the table one. The correspondence of the model has been therefore argued.

2. Investigation of the impact of coefficient of air excess on economy of the work and emission of harmful components of products of combustion after incineration of the coke oven gas.

Upon the incineration of coke oven gas at the boilers the atmosphere becomes saturated with large quantity of toxic agents, among them the most important are: nitric oxides (NO и NO2), sulfur oxides (SO2 и SO3), and, to a smaller extent - carbon monoxide (СО).

The equal concentrations of nitric oxides in the products of incineration of the coke oven gas in different temperatures in the combustion zone and the coefficient of air consumption were calculated in the course of investigations conducted.

With the view to choose the optimal value of the coefficient of air excess the heating engineering tests were carried out. In the course of these tests the percentage composition of the products of combustion before and afterwards water economizer were held

Using the data of the composition of the products of combustion, the air excess coefficient was counted up according to the oxygen formula.

During the investigation the concentrations of the harmful agents were defined, calculated after economizer.