SU958465A1 - Method for automatically controlling bitumen oxidation in converters - Google Patents

Description

 The invention relates to methods for automatically controlling the oxidation process of bitumen and can be used in the industry of building materials production and the refining industry.

There is a known method for automatically controlling the process of obtaining high-melting coal tar pitch by changing the air supply depending on the consumption of medium-temperature pitch and the quality of the final product with correction for the temperature of the liquid phase, and the supply of thermal pitch to the first reactor is corrected by the level of high-melting pitch in the last apparatus and the supply of pitch resin to the reactor is varied in a feed ratio depending on the flow rate of the C13 medium-temperature pitch.

However, the known method does not provide adequate safety precautions for the operation of the plant and obtaining a stable quality for this brand of bitumen, since when the process is conducted at crystalline temperatures of bitumen with heat, it cannot be quickly stopped (only by reducing the air supply, it is possible that there is a fire). In addition, the quality of the product is controlled when leaving the last reactor, i.e. with delay.

A known method for automatically controlling the oxidation process of bitumen in converters, in which the corresponding interval of oxidation temperatures of this bitumen grade is introduced, and when the upper temperature interval is reached, the air supply is automatically reduced while a part of the oxidized bitumen is taken out of the corresponding converter for pumping oh . User installation followed by feeding into the same converter 2.

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This method does not fully ensure proper safety due to the inertia of the system, and it is also necessary to keep in reserve the electrical power and

25 expensive equipment, in particular, refrigeration units, pumps, fans, pipelines.

Due to the fact that the process involves an urgent cooling;

30 decreases the reliability of system # 1. The aim of the invention is to ensure the specified quality of the finished product by increasing the reliability of the control system. . This goal is achieved by the fact that, according to the method of automatic control of the oxidation of bitumen in converters, which consists in regulating the supply of air with correction for the temperature of the oxidized bitumen, additionally regulate the supply of hungry bitumen depending on the oxidation time of the bitumen. The drawing shows a flowchart for implementing the proposed method. Line 1 and 2 are fed to the mix of Bit 5T and air, respectively. On line 3 cold (t-iSO C) bitumen having a mark of the finished product is fed. On line 4 comes the finished bitumen from the converter. The air supply control circuit to converter 5 consists of sensor 6, controller 7 and control valve 8, and for converter 9, sensor 10, controller 11 and control valve 12. For both converters, the air flow reference is maintained to maintain a predetermined interval oxidation temperatures are corrected by the temperature measured by sensor 13 and 14 in converters 5 and b, respectively, and the upper alarm level - by sensors, 15 and 16 in converters 5 and 6, respectively, valves 17 are installed on cold bitumen bitumen {ti80 ° C) and 18 which are from ryvayuts when applying cold bitumen to lower the upper critical temperature biguma. The blocking and automatic control of the corresponding valve 17 or 18 is carried out by the block 19 of the logical control system of industrial mechanisms of the type U11M-2, which receives signals from the controllers 8 and 11, as well as by the time control unit of the process control 20. Time correction unit process 20 consists of a positional temperature indicator 21 to a 2 position time relay 22. The method is carried out in the following way. The pre-heated bitumen is fed to the converter 5 and, successively through the converters 5. and 9, is oxidized to the desired bitumen mark. If the air flow rate deviates, oxidation, controlled by the sensor from a predetermined value, regulator 7 acts on the air supply valve 8, which increases or decreases the air supply for oxidation. The temperature of oxidation in the converter is monitored by sensor 13 at the same time, and when the variable temperature reaches the variable value, the regulator 7 comes in, which acts on the air valve 8 and covers it. At the same time, the signal from the regulator 7 enters the automatic control unit and locks the bitumen cooling mechanisms, as a result of which the valve 17 of the cold () bitumen, having the finished product brand, opens to the entire surface of the overheated bitumen at the top of the corresponding converter via radially located at the top converter mazutoprovody. When the temperature drops to the predetermined normal oxidation temperature, which is monitored by the sensor 13, the regulator 7 delivers a control signal to the air supply valve 8. and opens it by the amount necessary to ensure the predetermined air flow for oxidation, at the same time the valve 17 closes. The initial regime of bitumen oxidation. . In order to prevent an emergency case of overflow of the converter 5 when opening the valve 17 and supplying cold bitumen, installs, to it, the sensor of the upper emergency level 15.. When the upper alarm level sensor is triggered, the signal enters the logic system block 19, as a result of which the valve 17 is automatically closed and the supply of bitumen to the converter is stopped. The control and control circuit of valves 18 for converter 9 works in a similar way. Additionally (for reducing system inertia and enhancing safety), the control circuit for preliminary opening of cold bitumen supply valves 17 and 18 is introduced. According to the proposed method of automatic control of the bitumen oxidation process, the inertia of the system is 16 with. A temporary parameter is introduced that controls the temperature preceding the critical one on, and, if it does not decrease within 10 s, then a signal is sent from the correction unit by process control 20 to open the cold bitumen valves 17 and 18 by 50%.

(Valves with feedback rheostat). Independence from the local command and opening the valves 17 or 18 by 50%, the main circuit controlling and controlling the bitumen oxidation process continues to operate as described above, only if the temperature prior to the critical temperature of 5 ° C is maintained for more than 20 s or rises to the signal comes from the time correction unit 20 or from regulators 7 or 11 to the full opening of valves 17 or 18.

Example. Dt of obtaining the BIK-5 bitumen grade during the oxidation of the BNK-2 grade at a predetermined oxidation temperature range of 230-2 ° C is a continuous process, with the release of the BNK-5 bitumen grade. The time of bitumen oxidation is laid in the design of the installation of two converters through which bitumen passes with a stabilized feed of raw materials. When the bitumen temperature reaches 260 ° C in the converter 5, the valve is covered by a predetermined amount and at the same time (as described above) valve 17 opens and cold bitumen () fills the surface of the superheated bitumen in the upper part of the converter. As a result, part of the bitumen overheated, which is directly in contact with the open space of the converter, is automatically covered with cold () bitumen and ignition is prevented.

The oxidation process of the bitumen continues.

Previously, when the temperature of the oxidized bitumen reaches 225 °, the signal from the positional alarm goes to the 2-position time switch 22. If the temperature does not decrease for 10 seconds, then from the time correction node

a signal to open the corresponding valve 17, or 18 to 50% in the logic control unit 19; And if the temperature does not fall within 20 s, then from the correction unit by

time 20 enters the block 19 signal for the full corresponding valve 17 or 1.8 of the supply of cold bitumen, having the mark of the finished product. If the temperature

bitumen rises to 2bO ° C regardless of the time, signals from regulators 8 or 11 are received to open valves 17 or 18 completely.

As the bitumen temperature decreases

to which is monitored by the sensor 13, the regulator 7 delivers a control signal to the valve 8 and opens it by the amount necessary to ensure a given flow rate

air to oxidation, the valve 17 is simultaneously closed.

The installation returns to the optimal, safe mode of oxidation.

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Claims (2)

1. Author's certificate of the USSR 421713, cl. C 10 C 3/04, 1970. 2. Authors certificate of the USSR 2887944/26, cl. C 10 C 3/04, 1980