SU1242466A1 - Method of automatic control for process of sodium bicarbonate calcination - Google Patents

Description

The invention relates to the automatic control of the process of heat treatment of bulk materials in drum furnaces and can be used in the chemical industry in automating the process of calcining sodium bicarbonate in soda furnaces.

The purpose of the invention is to increase the service life of the furnace while stabilizing the quality of the finished product.

In the drawing, the scheme of implementation of the proposed method.

The control circuit contains regulator 1 of sodium bicarbonate consumption, regulator 2 of thermal elongation of the furnace drum, regulators 3 and 4 of the fuel and air consumption into the furnace, controller 5 and furnace temperature sensor 6, sensor furnace thermal elongation 7, Sensor 8-10 of sodium bicarbonate consumption, fuel and air into the furnace,

The method is described as follows.

An automatic dispenser using a flow regulator 1 delivers sodium bicarbonate to the soda furnace, where, upon calcination, one obtains coordinated soda and furnace gas,

The specified thermal load of the soda furnace, characterized by an indirect parameter — the elongation of the drum of the soda furnace — is supported by the lengthening controller 2, which is obtained from the controller 5, acting on the fuel consumption regulator 3 g The specified ratio between the fuel consumption and the primary temperature in the furnace they are supported by regulators 3 and 4 of fuel and air consumption. The flue gases formed during the combustion of fuel in the furnace of the soda stove give off heat to the barabanz of the soda furnace and, cooling down, go to the chimney. The preset temperature of the soda drum wall is maintained by temperature controller 5,

The knob of the controller 5 sets the task to the controller 2 of the drum elongation. The signal from the regulator is extended to the regulator 3 of the fuel consumption and to the regulator 1 of the sodium bicarbonate consumption.

The consumption of sodium bicarbonate is set according to the following relationship, depending on the elongation of the drum of the soda furnace:

Qsmk de q,

de

 bik

de - - with,

load of soda furnace by sodium bicarbonate, T / 4J elongation of the drum of soda furnace, mm,

five

0

five

0

0

S

0

S

C - constant, freezing

from in

sizes of soda furnace firebox.

The predetermined elongation is supported by the elongation controller 2, acting on the task of the fuel consumption regulator 3.

Correction of the task of regulating the temperature extension of the drum wall can be both discrete and analog. Preferred for stable operation of the soda furnace is a discrete correction. In this case, the regulator 5 is made with an adjustable dead band. This zone is tuned to the maximum permissible temperature of the drum wall, measured at a distance of 10-40% of the length of the heated part of the drum from its loading end, the value of which, for example, for a steel drum is. As the temperature of the drum 550 C increases, a correction regulator 5 is triggered, reducing the task of regulator 2 of the drum elongation, which leads to a decrease in fuel consumption and consumption of sodium bicarbonate.

Example. The process of calcining sodium bicarbonate is carried out in a stainless steel soda furnace having a length of 25 m and a diameter of 2.5 m,

At the initial moment, the thermal elongation of the drum is l 112 mm, the temperature of the drum wall measured at a length of 8 m (32% of the boot end) 520 ° C5 fuel consumption (fuel oil) is 550-600 kg / h. Depending on the initial moisture content of sodium bicarbonate, which varies constantly, and the fuel oil grade, sodium bicarbonate consumption is 11

l ::: „J.-. 1Д 7: 1 7 т / и

h iHK ts 14, j i.3, j, .j 1 / H,

where 14.25 is constant depending on

on the length and configuration of the furnace,

The system is stable for 2 hours. After 2 h, the setting of the heat 2 regulator 2 is changed.

nor up to a value of 110 mm. From the lengthening controller 2, a signal is simultaneously sent to the sodium bicarbonate flow controller 1 and the fuel consumption controller 3.

The consumption of sodium bicarbonate varies to a value of 13.25 ton / h, fuel consumption 525-575 kg / h.

After 5 hours of operation, the temperature of the drum wall increases to a value.

The controller 5 reduces the reference to controller 2 lengthening by 3.2%. It will be equal to 108 mm. From the extension controller 2, the signal simultaneously arrives at the sodium bicarbonate consumption controller 1 and the fuel consumption controller 3.

The consumption of sodium bicarbonate varies and is equal to 12.75 tons / h, and the fuel consumption decreases to 500-550 kg / h.

The temperature of the soda at the outlet of the furnace does not change at the same time and is 160 C.

After 30 minutes, the drum wall temperature, measured at a distance of 8 m from the boot end, reaches 525 C (the dead zone of the temperature regulator is 5%) and the regulator 5 changes the reference

Editor N. Rogulich

Compiled by G. Ogadzhanov

Tehred M. Khodanich Proofreader A. Obruchar

Order 3663/24 Circulation 450

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

 topp

42466. four

controller 2 is extended to the original. the elongation value of 1–10 m, the sodium bicarbonate consumption controller 1 and the fuel consumption controller 3 receive signals at the same time and the furnace starts operating as before; de 110 mm ,. Q ,, 13.25 t / h; Q. 525-575 kg / h.

The temperature of the soda at the exit of the furnace is 160 seconds. The content of the main substance in the finished product is 99.2%, i.e. soda ash is of the first grade.

Thus, the advantages of SP5 can be to increase its speed, since the latency of the system is reduced to 30 minutes, together 80-90 minutes by a known method. This leads to an increase in the service life of the drum of the soda furnace by preventing its walls from burning out. The service life of the drum between capital repairs is increased to 4 years (by the known method 3 g)

5 At the same time, the temperature of the final product leaving the drum is kept constant, which provides soda ash with stable quality indicators.

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Claims (2)

1. METHOD FOR AUTOMATIC REGULATION OF THE CALCINATION PROCESS. SODIUM BICARBONATE in a soda drum furnace by adjusting the fuel-air flow ratio by changing the air supply to the furnace, the fuel supply to the furnace, depending on the thermal elongation of the drum and the supply of sodium bicarbonate to the furnace, characterized in that, in order to increase the life of the furnace during stabilization quality of the finished product, additionally measure the temperature of the furnace wall, control the flow of sodium bicarbonate into the furnace in proportion to the thermal elongation of the drum and when the temperature of the furnace wall is reached, a steady value reduces the fuel supply to the furnace. 2. The method of pop. 1, characterized in that the temperature of the furnace wall is measured at the loading end of the furnace at a distance of 0.1-0.4 from the total length of the heated part of the furnace drum. Furnace gas SODA Lying air Tollio SU ,,,. 1242466