Технические науки/12. .Автоматизированные системы
управления на производстве.
Student Dubytska K., Candidate
of Engineering Sciences Ladieva L.
National
technical university of Ukraine “Kyiv Polytechnic Institute”, Ukraine
Сontrol
of tubular furnace in a process of catalytic
reforming
Catalytic reforming is a chemical process used to convert petroleum
refinery naphthas distilled from crude oil (typically having low octane
ratings) into high-octane liquid products called reformates, which are premium
blending stocks for high-octane gasoline. The process converts low-octane
linear hydrocarbons (paraffins) into branched alkanes (isoparaffins) and cyclic
naphthenes, which are then partially dehydrogenated to produce high-octane
aromatic hydrocarbons.
Approximately 65-90% of total refineries energy for heating is provided
by furnaces. Chemical industries such as oil, gas and petrochemical comprise a
set of diverse heating and cooling processes in many of them it is necessary
that some of liquids to be heated to a certain temperature. This process is
generally done by furnaces. Furnaces, in essence, are a kind of heat exchanger
that transfer the thermal energy obtained from burning fossil fuels in a closed
space to a process liquid which in coils or locked up pipe flows.
So
tube furnace is one of the most important refinery process units. Because the
quality of oil depends on the reliability and stability of supply of thermal
energy.
Shown
in figure automation scheme consists of contours such as:
- 1 contour of providing
air flow control;
- 2 contour of providing
control spending of gasoline and the ratio of air flow;
- 3 contour of providing
temperature control at an input in stabilization column;
- 4 contour of provides
control and signaling temperature gases emitted into the environment.
This
scheme can be used as part of the automation process of catalytic reforming.
251658240
Automation scheme
A
process heater is a direct-fired heat exchanger that uses the hot gases of
combustion to raise the temperature of a feed flowing through coils of tubes
aligned throughout the heater. Depending on the use, these are also called
furnaces or fired heaters. Some heaters simply deliver the feed at a
predetermined temperature to the next stage of the reaction process; others
perform reactions on the feed while it travels through the tubes.
The
radiant tubes, either horizontal or vertical, are located along the walls in
the radiant section of the heater and receive radiant heat direct from the
burners. The radiant zone with its refractory lining is the costliest part of
the heater and 85% of the heat should be gained there. This is also called the
firebox.
Rather
than hit the radiant section directly, the feed charge enters the coil inlet in
the convection section where it is preheated before transferring to the radiant
tubes. The convection section removes heat from the flue gas to preheat the
contents of the tubes and significantly reduces the temperature of the flue gas
exiting the stack.
References:
1. S. Mussati, Juan
I."Manassaldi,Mixed Integer Non Linear Programming Model For The Optimal
Design Of Fired Heaters",Applied Thermal Engineering, Vol. 29, pp.2194-2204,
2009.
2. Alireza bahadori, Hari B.Vuthaluru. "Novel predictive tools for
design of radiant and convection sections of direct fired heaters",
Applied Energy, Vol. 87, pp.2194-2202,2009
3. Гейтс Б. Химия каталитических процессов [Текст] / . Гейтс Б., Кетцир Дж., Шуйт Г. Пер.с англ., М., Мир, 1981, 551с. –
Библиогр.: с. 441-550. – 5000 пр.