SU1649229A1 - Method of control of firing process in fluidized bed furnaces - Google Patents

Abstract

The invention relates to methods for controlling calcination processes in fluidized bed furnaces and can be used in the cement industry, in the building materials industry, in the chemical industry and other areas during calcination of materials in a fluidized bed furnace. The goal is to improve the quality of regulation. To do this, measure the temperature of the boiling layer, over which the flow of coolant is changed, measure the pressure under and above the layer of material, calculate the pressure difference, determine the corresponding dispersion, extract the constant component from the pressure difference, over which the amount of material being unloaded, and the change in the air supply are inversely proportional to the dispersion until it reaches a value of 0.16-0.23. 2 Il.

Description

The invention relates to methods for regulating calcination processes in fluidized bed furnaces and may find application in the cement industry, in the building materials industry, the chemical industry and other sprays when calcining materials in a fluidized bed furnace.

The purpose of the invention is to improve the quality of regulation.

The essence of the method is as follows.

With an increase in the speed of the liquefying agent after the beginning of boiling in a fluidized bed furnace, the boiling mode changes to a pulsating one; Experimental dependencies were obtained on the experimental setup of the Research Institute of Cement on clinker with a granule size of 5-10 mm. It is known that with the transition of the fixed bed to the boiling one, its thermal conductivity first increases, reaches a maximum with the degree of blow up T, 5-1,75,3 then the thermal conductivity again drops to very small values, which is explained by an increase in boiling bed porosity .

At the same time, the increase in the porosity of the fluidized bed in comparison with the porosity of the dense layer is 0.2-0.26. Since the volume increase is 1.5-1.75, the amplitude of sinusoidal pulsations has a range of 57-86 mm for a dense layer of 230 mm and a range of 75-112 mm for a dense layer of 300 mm. For the average amplitudes of pulsations, the amplitudes of the dynamic component of the layer resistance, calculated by the formula

V2

A R AL 2

 Elgde / Zsl - the density of the layer with

 1000 kg / m3;

d v l g average speed of granules, m / s;

A - amplitude, m; f - frequencies, Hz, equal to a layer of 230 mm

APi

1000 0.42 9.8 -2

8.8 mm water; for

300 mm layer - D WG

1000 -0.47

 11 mm

9.8 -2 water column

At the optimal porosity of the layer, the experimental and calculated values of the ripple resistance of the layer practically coincide.

Dispersion sinusoidal component of the resistance layer

„АР2

respectively for a dense layer of 230 and 300 mm,

The operation of the reactor with a rational height of the dense layer from 200 to 300 mm occurs in the optimal firing mode with dispersion values in the range of 0.16-0.23, which exceeds the limits for the use of the coolant in the fluidized bed.

Experimental studies have established that the constant component of the layer resistance characterizes the amount of material in the layer, and the dispersion value of the layer resistance is the porosity of the layer, the intensity of its boiling, and heat and mass transfer. These parameters allow choosing the most rational fluidized bed mode for the clinker burning process.

The resistance of the layer is measured by selective pressure devices under and above the layer, outside the material.

Figure 1 shows the block diagram of the device that implements the method; 2 shows the dependences of the resistance of the amplitude layer and

the frequency of its pulsations on the amount of material in the layer.

The sintering of the components of the raw mix and the formation of clinker occurs in the fluidized bed of the furnace 1 at 1350 ° С. When the temperature in the fluidized bed deviates from the indicated difference, the signals of the thermocouple 2 and the setpoint 3 of the temperature from the adder of the regulator 4 are fed to its regulating

a unit that, using the actuator 5, reduces or increases the flow of the coolant until the indicated signals become equal. Block 6 continuously measures the pressure difference under and

over the layer of material (resistance of the layer) in the furnace 1. The selected constant component of the signal of block 6 is supplied to the regulator simultaneously with the signal of setpoint 8 using the resonant filter in block 7

9, controlling by means of the actuator 10 the discharge of the finished material from the furnace 1 is proportional to the deviation of the signals. In block 11, the variance of the difference signal is determined. In the controller 12, it is compared with the value of its predetermined setpoint 13. In the presence of a difference in signals, the actuator 14 increases or decreases the air supply to the furnace 1. This ensures an optimal firing mode with rational quantities of a fluidizing agent and fluidized bed material.

The optimum firing mode is achieved with a constant component of the resistance of the layer, equal to 200-300 mm water. and at the dispersion values of the layer resistance 0.16-0.23.

The method provides reliable control and regulation with the required accuracy. Adjustment accuracy will increase by 5%. Since the coefficient of thermal conductivity is proportional to the porosity of the layer when it varies within small limits from the optimum, the coefficient of heat utilization in a fluidized bed increases by 5%. The clinker kiln productivity increases by the same amount due to the process intensification.

Claims (1)

Invention Formula The method of regulating the firing process in fluidized bed furnaces, including adjusting the flow of coolant according to the measured temperature of the fluidized bed and change in air supply, characterized in that, in order to improve the quality of regulation, the pressure under and above the material layer is measured, the pressure difference is calculated, the corresponding dispersion is determined, the constant component is separated from the pressure difference. according to which the amount of the material being discharged is changed, and the change in the air supply is inversely proportional to the dispersion until it reaches a value of 0.16-0.23. Fig.} & P, 3 np8st Heat carrier  in cm