SU1752726A1 - Method of process control in fluidized bed roasting of sulfide materials - Google Patents

Abstract

Usage: automatic regulation of roasting processes of sulphide raw materials in fluidized bed furnaces. Essence: automatic regulation of the firing process of sulphide materials in a fluidized bed furnace involves stabilizing the flow rate of blowing and controlling the process temperature by changing the flow rate of the material fed to the furnace. At the same time, the material flow rate is changed according to the temperature of the kiln gases at the exit of the furnace, setting the controller change depending on the temperature difference of the firing gases at the exit from the furnace and in front of the waste-heat boiler 1 sludge.

Description

The invention relates to methods for controlling the firing process of sulphide materials in a fluidized bed furnace (CS) and can be used to automate CS furnaces in the production of sulfuric acid, in non-ferrous metallurgy and other industries.

During sintering of sulphide materials in a fluidized bed, deviations and average temperatures of the fluidized bed and the kiln gases at the exit from the furnace affect the quality of the process, as well as the operation of subsequent equipment along the gas path and thus the technical and economic indicators of production. temperatures of the fluidized bed and obzhgovyh gases solid particles can melt and stick on the surfaces of the waste heat boiler, disrupting its operation; as temperature decreases, sulfur recovery from raw materials (sulphide materials) decreases.

There is a known method for controlling the firing process of sulphide materials in fluidized bed furnaces, including measuring the temperature of the fluidized bed and the temperature of the firing gases in the furnace and the change in the supply of material to the furnace depending on the temperature difference.

but

The disadvantage of this method is that the temperature of the firing gases and the difference between the temperatures are not uniquely associated with the temperature of the fluidized bed. Thus, a change in the granulometric composition of materials changes the amount of entrainment and, accordingly, the temperature of the firing gases due to burnout of entrainment, while the temperature of the fluidized bed changes by an order of magnitude.

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slower than the firing gas temperature

The closest to the technical essence and the achieved effect to the proposed is a method of controlling the process of burning sulphidine materials in fluidized bed furnaces, including measuring the temperature of the fluidized bed and the kiln gases at the exit of the furnace and changing the flow rate of the material fed into the furnace, based on the measured temperature fluidized bed and the rate of change of the measured firing gas temperature at the exit of the furnace.

The method provides sufficiently high quality maintenance of the temperature of the boiling water at the expense of such two-channel control, since the input disturbances are quickly compensated in the circuit for supplying the material to the firing gas temperature, since the firing temperature at the exit from the furnace is 1–8 min earlier than the temperature boils, responds to input

The disadvantage of the known control method consists in incomplete extraction of the seoi from the material due to the fact that the temperature of the fluidized bed and / or the firing gases (especially as a derivative) at a fixed point along the gas path does not characterize the ciencHU completeness of the firing process and the position of the firing reaction termination zone. The latter may be located in the furnace space, gas path or even in the recovery boiler, which is an emergency mode (besides, due to the extreme nature of the static characteristic isc i (Q) o em high load becomes uncontrolled e- by direct material flow through the channel - tempera- ture, since in this transmission ratio 1 dt / dQ tends to zero, or even changes the sign)

The purpose of the invention is to reduce the loss of sulfur.

This goal is achieved by the fact that, according to the method of controlling the calcining process of sulfide materials in the fluidized bed, including measuring the temperature of the kiln gases at the exit of the furnace and changing the flow rate of the material fed into the kiln, based on the measured temperature, the temperature difference of the kiln gases is additionally measured the exit from the kiln (at the beginning of the flue) and to the entrance to the waste-heat boiler, sum the value of the firing gas temperature to the BYKHODR from the kiln with a value proportional to the measured firing temperature difference gases, and the change in material

oven is carried out depending on the amount received

The invention takes into account the peculiarities of the process and the firing unit in the fluidized bed. In general, the temperature of the firing gases at any one point of the unit and the gas path does not unambiguously characterize the temperature of the layer and gases at other points and the degree of completeness of the reactions. completion of firing reactions (burnout of ash), which is determined by the magnitude of the separation of temperatures along the length of the flue

Information in combination with information about the temperature of the firing gases at the exit of the furnace tor 1 fully characterizes the process coexistence - both the temperature level and the position of the end of the firing reactions and, accordingly, its efficiency. So, if the temperature of the gases before the recovery boiler is higher than at the exit of the furnace, this means increased unps, which continues to burn out at the end of the flue. The same temperature of the gases on the KNOWN of the furnace and before entering the waste-heat boiler means that the ash in this section has time to burn out, and alley gases partly cooled due to heat transfer through the walls of the flue gas temperature decrease firing the entire length of the flue means that the practical process is terminated in the furnace space, or the beginning of the gas flue, which corresponds to reduced load.

Controlling the firing process by feeding the mertarpal into the kiln based on a complete parameter including interconnected leads “/ py” —the tori kiln temperature and a value proportional to the temperature difference of 1 Dt.hg allows you to simultaneously maintain the tor process temperature at some optimum for specifically about material range, and the position of the zone of completion of the firing reaction in a certain range along the gas path of the unit CS

The drawing shows the apparatus implementation scheme of the proposed method

The system for controlling the firing of sulphide raw materials in the fluidized bed furnace 1 with the flue 2 and the waste-heat boiler 3 includes a flow rate stabilization loop, containing a flow meter 4, a regulating unit 5 and an actuator (regulator) b, and a temperature control system containing double thermocouple 7 and single thermocouple 8 installed respectively at the exit of the furnace and in front of the waste-heat boiler

the regulating unit 9, the motor 10 drive feeder 11 sulfide material. In addition, the system contains a unit 12 for measuring the difference in temperature of the firing gases at the exit from the furnace and in front of the recovery boiler, a filter 13 (for suppressing the masses) and a unit 14 for multiplying by a constant factor.

One of the thermocouples 7 is connected to one of the inputs. Variable of the regulating unit 9, the other thermocouple 7 and the thermocouple 8 are connected to the inputs of the temperature difference unit 12, the output of which is connected to the input of the filter 13, and the output of the filter 13 is connected to the input of the block 14 intelligently - not a constant coefficient. The output of block 14 is connected to another input. Variable of the regulating block 9. To the input of the reference is connected the output of the temperature setter (not shown).

The connections of the control system elements are made so that the change in the temperature of the firing gases affects the change in the consumption of raw materials as follows:

an increase in the temperature of the kiln gases at the exit of the furnace causes a decrease in the supply of material to the furnace;

an increase in the temperature difference between the firing gases at the exit from the kiln and at the end of the flue (before the waste-heat boiler) A t or - tori - tor2 causes an increase in the supply of material to the kiln.

The control system works as follows

In the steady state, all process parameters are stabilized — the flow rate of the material blow (at its constant composition), the firing temperature of the path through the path, and the position of the reaction completion area.

In the event of a disturbance, for example, with an increase in material consumption caused by a change in the particle size distribution of the material (since this changes the characteristics of the plate feeder), the temperature of the firing gases at the exit of the furnace increases, while due to the movement of the afterburning flame at the beginning of the duct (increases with) both the temperature of the firing gases at the exit from the furnace, and the temperature difference between the firing gases at the exit from the furnace and in front of the waste-heat boiler

As a result of the imbalance of the signals at the input of the regulating unit 9, the output signal and, accordingly, the material consumption change by changing the rotational speed of the motor 10 for the plate feeder 11 until a new steady state of the firing process is reached. In this case, due to the increase in the degree of entrainment of the material and the movement of the end zone of the reaction to the beginning of the flue duct, equilibrium will be achieved at higher temperatures toi 1 and the difference

At tori tor2.

The magnitude of the range of variation of tori and the associated temperature difference Ator, characterizing the position of the zone of termination of the burning reaction, is specific to the concrete; the regatta is determined by the coefficient k.

The effect of the value of the coefficient k on the ratio of the ranges of change tor.1 and Ator in the control process is as follows. Since the algebraic sum of the temperature tori and the value proportional to the temperature difference k At0r in the steady state must be equal to the given value tsa, i.e.

Hzd tori - k Ator const (which corresponds to the order of connecting elements of the system to the regulating unit, based on the above conditions affecting the equation of magnitude on the change in material consumption), it is obvious that the range of temperature change tori at a fixed range of variation A tor that larger than k.

Thus, with increasing k in the steady state, the deviation of tor i increases accordingly and the range of variation of At0r decreases, and vice versa, a decrease in k leads to a decrease in the range of variation of tori with an increase in the range of Ator.

Since the maximum and minimum values of Ator are known for a particular unit, determine the allowable position of the zone of completion of firing reactions along the gas path of the unit, by choosing the value of the coefficient k, you can set the limits for moving the zone of completion of the reaction of firing and temperature variation at the exit from the furnace within the specified limits for different loads (within the acceptable range).

Using the proposed method of controlling the firing process will reduce the routine sulfur loss with calcine from 0.8 - 1.0% on average by 0.1 - 0.15%, which will save about 300 tons of pyrite per year per CS furnace; increase the aggregate campaign due to more rigid stabilization of the temperature regime; improve the degree of contact of sulfur dioxide by 0.005% due to the increased stability of the firing process.

Claims (1)

Claim Method A method for controlling the firing process of sulphide materials in a fluidized bed furnace, including measuring the temperature of the firing gases at the exit of the furnace and changing the flow rate of the material fed into the furnace, based on the measured temperature, characterized in that, in order to reduce sulfur losses, The temperature difference between the combustion gases at the exit from the furnace and at the entrance to the waste heat boiler is summarized. The temperature values of the firing gases at the exit from the furnace are summed up with a value proportional to the measured temperature difference. p, and the change in the flow rate of the material fed into the furnace is made depending on the amount received. guv four 3d IB 1 & at