SU1044931A1 - Method of automatic control of drying process - Google Patents

Abstract

A method for automatic drying of the drying process in a drum dryer equipped with a heater and bag filters by changing the supply of energy carriers to the heater depending on the temperature of the dust and the dried material, so as to increase control accuracy, measure the speed, change the flow rate of wet material, determine its sign, and, depending on the latter, change the air flow to the preheater and to blow the bag filters, and with a positive value of speed from Changes in the consumption of wet material; these changes are made with a time delay. OtffXfC f og n1 reru CD 00

Description

The invention relates to a drying technique, namely to automating the process of drying bulk materials.

There is a known method for automatically controlling the drying process with bulk materials in the dryers, based on introducing a leading pulse in terms of the derivative of temperature into a zone of constant drying rate, affecting the flow rate of secondary air supplied to the furnace, and adjusting the temperature of the heat carrier. In order to improve the accuracy of adjusting the fractional process of the euilka during the direct flow and countercurrent movement of the drying agent and the survival: on the quantitative distribution of the drying agent in the flow and countercurrent, and the leading impulse in the derivative of the temperature affecting the secondary air flow is taken as the zone of constant drying rate of the selected fine fraction of the material}

However, this method does not provide the required quality of regulation.

Closest to the proposed technical essence and the achieved result is a method of automatic control of the drying process of bulk materials. controlling the temperature of the dust and the parameter of the dried material, which characterizes the drying process, and the subsequent impact on the result of the comparison of these signals on the energy input to the drying. At the same time, as a parameter characterizing the drying process, a signal is used based on the temperature of the dried material, and when comparing the signals, the difference between the measured temperatures is determined followed by correction for the temperature of the dust 2.

The disadvantage of this method is that the control system does not provide for reacting to the dust collection system, because it does not take into account the load on the dust collection equipment, which leads to loss of product from the fluid and the atmosphere, dusty products,

The purpose of the invention is to increase the accuracy of regulation.

This goal is achieved by the fact that according to the method of automatic control of the drying process in a drum dryer equipped with a heater and bag filter.

Depending on the temperature of the dust and the dried material, the rate of change in the flow rate of the wet material is additionally measured by changing the energy supply to the preheater, its sign is determined, and the air flow to the preheater and to the purge of bag filters is changed depending on the latter The value of the rate of change of the damp material moisture rate is indicated with a delay of ps of time.

The drawing shows the sche. Device, implementation 1: dego spoO "

The device contains a heater 1 of the heat transfer medium (for example, a heater), a dryer drum 2, a cyclone 3 and bag filters 4 for collecting dust.

The automatic reh vlirovavi system includes a sensor with a wet material flow rate controller and an actuator 6, a differentiation unit 7, a key 8, a logic unit 9, a delay unit 10, a regulator 11 and an actuator 12 for heating the heater 1, the regulator 13 and an executive a bag filter control mechanism 14, dust temperature sensors 15 and dried material 16, an adder 17, a regulator 18, and an actuator 19 for supplying a heating agent to the heater 1.

In order to reduce the loss of the finished product from the fuel and to reduce environmental pollution by increasing the consumption of wet material (positive sign of the derivative signal proportional to the material consumption) supply of heat carrier to the suspect and regulation of the pulse mode of operation (period and duty cycle of air supply to purge the sleeves) bag filters produced with a time delay. Moreover, the functional dependence of the signal for the flow of coolant and the mode of operation of the bag filters is functional:

y correction signal; .

X-- proportional signal

the course of wet material; x is a signal proportional to the rate of change of flow

the wet material, Tj, is the constant of the time of the differentiation unit 7;

 - constant block 1 time

delays;

those. (x) and f {xJ, where F is the coolant flow;

 period and duty cycle of shaking the filter sleeves.

Tafcoe control eliminates the unreasonably high flow rate of heat carrier (air) at the initial moment of the transition period and, as a result, the blowing of material, which allows stabilizing the load on the pier, resistance of bag filters and preserving the trapping ability of the latter.

With an increase in the consumption of wet material, a signal proportional to this change, through block 7, enters the key 8 and block 9 of the logic. Since the sign of the derivative of the signal is proportional to the consumption of wet material ,. +, the output signal of the block 9 will switch the key 8 and the output signal of the block 7 through the delay block 10 enters the stabilization controller 11, corrects the flow rate of the coolant, and the regulator 13, the output signal of which with the help of the regulator 14 will change the mode (period and duty cycle) pulse purging bag filters.

With a decrease in the consumption of wet material, the output signal of the block 7 is fixed on the key 8 and the block 9 of the logic. Since the sign of the derivative of the signal proportional to the consumption of a wet material is, the output signal of block 9 switches key 8 and the output signal of block 7, the delay block 10 min, goes to the controllers 11 and 13. with increasing, balancing the supply energy is produced by changing the amount of energy carrier (steam) according to the temperature of dust, controlled by sensor 15, corrected by the temperature difference between dust and material controlled by sensor 16. Herewith, correction is carried out using torus 18 and valve 19.

Example. The drying process of a zeolite of the NaA type in production with a capacity of about 30 thousand tons of product per year is characterized by the following parsmeters.

Consumption of wet material 5060 kt / h; air consumption in the heater re-77000 nm3 / h; the amount of dry material after drying 3800 kg / h; the temperature of the dried material is 55 ° C; the temperature of the dust-air mixture after the dryer is 60 ° C; the dust content in the emitted air into the atmosphere is not more than 1.7 mg / nm.

.In case of an increase in the consumption of wet material by 160 kg / h, the signal, which is proportional to this change, enters key 8 and block through block 7.

9logiki. Since the sign of the derivative of the signal is proportional to the consumption of wet material, +, the output signal of block 9 will switch the key 8

and the output of block 7 will go to block 10 of the delay. With this block

10 delay produces a delay in the signal from block 7 for 10-60 s (the delay time is set by the constant time of the object). From the delay unit 10, the signal goes to the controller 11, the output of which changes the flow rate of air supplied to the heater by 2400. At the same time, the output signal of the unit 10 is supplied to the regulator 13, which will increase the period and duty cycle of the pulsed sleeves, through the valve 14 in the bag filter 4. At the same time, the degree of purification of the dust-air mixture by the bag filter will increase from 96% to 98%.

Due to all these measures, it is possible to reduce the dust emission by 0.2 g / nm into the atmosphere, which, at a product cost of 300 rubles / ton and with a productivity of 30 thousand tons per year, will save about 66 thousand rubles per year by 1 unit due to reduce product loss.

Claims (1)

METHOD FOR AUTOMATIC REGULATION OF THE DRYING PROCESS in a drum dryer equipped with a heater and bag filters by changing the energy supply to the heater depending on the temperature of the dust and the dried material, due to the fact that, in order to increase the accuracy of regulation, measure the speed, changes in the flow rate of wet material, determine its sign, and depending on the latter, change the air flow to the heater and to purge the bag filters, and with a positive value of the speed change As the consumption of wet material, these changes are delayed. Bvspoc t SU ..1044931