RU2791526C1 - Flare chamber - Google Patents

Abstract

FIELD: oil and gas.

SUBSTANCE: invention relates to devices for producing flue gases with controlled temperature for heating equipment in the chemical, oil refining, gas processing, food and agricultural industries. The flare chamber is equipped with a compression chamber and an additional mixing chamber installed in series after the mixing chamber of the coolant and the cooling agent. The compression chamber is made in the form of a container tapering towards the additional mixing chamber, wherein the cross-sectional dimensions of the additional mixing chamber at the junction with the compression chamber are larger than the cross-sectional dimensions of the compression chamber at the point of its attachment to the additional mixing chamber. The refrigerant supply system is in communication with the main and additional mixing chambers.

EFFECT: invention makes it possible to regulate the temperature of the obtained coolant over a wide range while simultaneously increasing the completeness of fuel combustion, as well as increasing the flue gas temperature uniformity.

6 cl, 1 dwg

Description

SUBSTANCE: invention relates to devices for producing flue gases with controlled temperature for heating equipment in the chemical, oil refining, gas processing, food and agricultural industries.

Flue gas heated process furnaces are the main energy consumers in the oil refining, petrochemical and chemical industries. Increasing efficiency when using them allows you to get significant savings and significantly reduce energy costs in the overall balance of production costs. The most important parameter that makes it possible to achieve high efficiency in the operation of heating furnaces is an increase in the completeness of fuel combustion and the ability to control the combustion process and flue gas temperature over a wide range. At the same time, the parameters of the combustion process, its stability, are influenced by many variable factors, the change of which during the combustion process leads to noticeable fluctuations in the characteristics of flue gases, which leads to uneven completeness of fuel combustion and flue gas temperature changes (E.R. Saifullin. "Optimization of thermodynamic characteristics of the combustion process of gaseous fuel of the methane series of variable composition for ground-based power plants", Dissertation of Candidate of Technical Sciences, Kazan, 2018).

For heat-exchange equipment using flue gases as a heating agent, an urgent problem is the high temperature of the burner flame and significant temperature unevenness of flue gases, which leads to uneven heating of process equipment (E.A. Dmitriev, E.P. Morgunova, R.B. Komlyashev, "Heat exchangers for chemical industries", Mendeleev University of Chemical Technology, Moscow, 2013)

To solve this problem, furnaces are used, the volume of which exceeds the volume of the burner flame by tens and hundreds of times, and the walls of the furnaces are covered with rows of pipes with a heated agent flowing in them. The recirculation of already cooled flue gases with their supply to the furnace is also used. Such technical solutions make it possible to regulate the temperature of flue gases within certain limits, but not enough and, in addition, lead to a decrease in the completeness of fuel combustion and to large dimensions of equipment (http://chemengrkhtu.ru/materials/lectures/Lec.%2015.pdf).

The widely used technical solution of flue gas recirculation to the furnace to control furnace processes is used to achieve a number of technological and environmental goals:

- reducing the temperature of gases at the outlet of the furnace at high loads, as well as for better distribution of gases over the cross section of the furnace, maintaining the calculated temperature of combustion products at the outlet of the furnace, increasing the uniformity of the temperature of the gas flow along the depth of the furnace;

- equalization of the temperature profile of flue gases at the outlet of the furnace in powerful boilers by supplying flue gases through slots in the upper part of the combustion chamber;

- regulation of flue gas temperature at the outlet of the furnace;

- reducing the level of formation of nitrogen oxides is achieved by lowering the temperature level of the combustion process by introducing flue gases directly into the furnace in its lower part or through burners;

- preventing the formation of nitrogen oxides by introducing recirculating flue gases through the burners as an insulating medium separating the flows of the aero mixture and secondary air, as well as by diluting the air with a neutral medium and reducing the concentration of the oxidizer in the flame.

The recirculation of flue gases into the furnace affects not only the aerodynamic processes in the furnace, but also changes the composition of flue gases and significantly increases their amount.

However, the use of flue gas recirculation to the furnace reduces the boiler efficiency by an average of 0.03-0.06% for every 1% recirculation ratio (https://studme.org/319402/prochie/vyravnivanie_temperatury_dymovyh_gazov_vyhode_topki).

A device for heating with flue gases is known, containing a burner, a combustion chamber with a flue gas exhaust system connected to a flue gas recirculation channel (SU1186913).

A flue gas heating device is known, comprising a housing with a combustion chamber located inside, and the outlet of the combustion chamber is connected to the inlet of the heat exchange chamber. The device contains a recirculation fan, the inlet of which is connected to the outlet of the heat exchange chamber, and the outlet is connected to the inlet of the combustion chamber (US3854455).

However, flue gas recirculation does not allow increasing the completeness of fuel combustion, sufficiently widely and accurately control the flue gas temperature.

The closest technical solution to the proposed one is a coolant preparation device, including a burner, a flame tube and a mixing chamber of the coolant and coolant connected in series with the coolant supply system (RU177784).

The disadvantages of this device include the limited ability to control the temperature of the flue gases before they are fed to the heated equipment and the insufficient completeness of fuel combustion. The disadvantages are due to the fact that flue gas temperature control is carried out by supplying exhaust flue gases with a sufficiently high temperature to the mixing chamber, and the amount of recirculation gases is limited by the heat transfer capacity of the device. At the same time, the exhaust gases cannot provide a complete post-oxidation of the combustion products in the mixing chamber, since the oxygen content in them is low, with a high temperature fluctuation of the flue gases.

The technical result achieved by the invention is to expand the range and accuracy of temperature control of the working flue gases, increase the temperature uniformity of the flue gases supplied to the process equipment, as well as increase the completeness of fuel combustion.

The temperature of the flue gases in the combustion chamber can reach 1300-1900°C, and the temperature of the flue gases for heating equipment is in the range of 400-1700°C. Therefore, expanding the temperature control range of the resulting coolant with a simultaneous increase in the uniformity of the temperature field of the coolant is an urgent task, the solution of which increases the uniformity and stability of heating and maintaining the specified temperatures of the process equipment.

The technical result is achieved by the fact that the flare chamber is equipped with a compression chamber and an additional mixing chamber, connected in series with each other and installed after the mixing chamber of flue gases and a cooling agent, the compression chamber being made in the form of a container tapering towards the additional mixing chamber, and the cross-sectional area internal space of the additional mixing chamber at the junction with the compression chamber is larger than the cross-sectional area of the internal space of the compression chamber at the point of its attachment to the additional mixing chamber, while the cooling agent supply system is additionally communicated with the additional mixing chamber. The ratio of the maximum length to the maximum value of the cross-sectional area of the internal space of the mixing chamber is in the range of 1:5-20. The inner surface of the mixing chamber has the shape of a cylinder or prism. The ratio of the maximum and minimum cross-sectional areas of the internal space of the compression chamber is within 3-5, and the ratio of the maximum length of the internal space of the compression chamber to the ratio of the indicated areas does not exceed 2. The internal surface of the compression chamber has the shape of a truncated cone or a truncated pyramid. The junction of the coolant supply system with the mixing chamber is located near the outlet of the flame tube.

These features of the invention are essential.

In the compression chamber, flue gases are dynamically compressed, which leads to an increase in the completeness of fuel combustion and an increase in flue gas pressure and, in turn, to accelerate heat transfer processes at high gas pressure and temperature, thereby increasing the uniformity of the temperature field. Due to the sharp expansion of the compressed flue gases in the additional mixing chamber and the addition of a cooling agent, they are cooled to the desired temperatures. Expansion of flue gas temperature regulation range occurs due to regulation of the flow rate supplied to the main and additional chambers for mixing flue gases with a cooling agent, as well as regulation of the redistribution of the volume of supply of a cooling agent between the main and additional mixing chambers.

The figure shows a general view of the flare chamber in section.

The flare chamber includes a burner 1 with a flame tube 2, which is connected to the main mixing chamber 3. At the end of the mixing chamber 3, a compression chamber 4 is installed, made in the form of a truncated cone or a truncated pyramid, directed by its large base to the mixing chamber 3. The other side of the chamber 4 is connected with an additional mixing chamber 5. The cross-sectional area of the internal space of the additional mixing chamber 5 at the junction with the compression chamber 4 is greater than the cross-sectional area of the internal space of the compression chamber 4 at the point of its attachment to the additional mixing chamber 5. The ratio of the maximum length to the maximum value of the cross-sectional area the internal space of the mixing chamber 3 is in the range of 1:5-20. This ratio is chosen based on the optimal geometry of the internal space of the chamber 3, which should create the best conditions for uniform mixing of the flue gases and the cooling agent while maintaining sufficient kinetic energy of the gases to ensure optimal dynamic compression in the compression chamber 4. The inner surface of the mixing chamber 3 has the shape of a cylinder or prisms.

The ratio of the maximum and minimum cross-sectional areas of the internal space of the compression chamber 4 is in the range of 3-5, and the ratio of the maximum distance between these sections to the ratio of these areas does not exceed 2. These parameters are selected experimentally to ensure the optimal pressure in the compression chamber, at which , on the one hand, excessive excess pressure is not created in the mixing chamber, which worsens the combustion conditions in the flame tube 2, and on the other hand, sufficient gas density is maintained to equalize temperatures.

A cooling agent supply system is connected to mixing chambers 3 and 5, consisting of a fan 6, pipelines for supplying a cooling agent, valves 7, 8, 9 and 10, a branch pipe 11 for introducing a cooling agent into chamber 3, a channel 12 for introducing a cooling agent into an additional mixing chamber 5 The connection point of the branch pipe 11 of the cooling agent supply system with the mixing chamber 3 is located near the outlet of the flame tube 2.

Air or any other gas, or water or other liquid is used as a cooling agent.

The device works as follows.

The burner 1 supplies a mixture of fuel and air into the flame tube 2, where a combustion flame is formed, partially passing into the main mixing chamber 3, where air or another cooling agent enters through the nozzle 11. In chamber 3, a flow of a mixture of flue gases and cooling air is formed, which enters the compression chamber 4. In chamber 4, a mixture of cooling agent and flue gases is dynamically compressed, which leads to an increase in pressure and additional oxidation (afterburning) of combustion products. With increased pressure, heat transfer is accelerated and the uniformity of the temperature field increases. From chamber 4, the compressed coolant enters an additional mixing chamber 5, which has an extension at the inlet. Due to the sharp expansion of the compressed coolant in the chamber 5 and the addition of a cooling agent through the channel 12, the coolant is cooled to the desired temperatures. The coolant temperature is controlled by controlling the volumes of coolant supply to mixing chambers 3 and 5 by means of fan 6 and valves 7, 8, 9 and 10.

The application of the claimed design allows you to control the temperature of the resulting coolant over a wide range while increasing the completeness of combustion of the fuel and increasing the uniformity of the temperature of the gases.

Claims (6)

1. The flare chamber, which includes a burner, a flame tube and a mixing chamber of a heat carrier and a cooling agent connected in series with a cooling agent supply system, characterized in that it is equipped with a compression chamber connected in series with each other and installed after the mixing chamber of flue gases and a cooling agent and an additional mixing chamber, wherein the compression chamber is made in the form of a container tapering towards the additional mixing chamber, and the cross-sectional area of the internal space of the additional mixing chamber at the junction with the compression chamber is greater than the cross-sectional area of the internal space of the compression chamber at the point of its attachment to the additional mixing chamber, wherein the coolant supply system is also in communication with the additional mixing chamber. 2. The flare chamber according to claim 1, characterized in that the ratio of the maximum length to the maximum value of the cross-sectional area of the internal space of the mixing chamber is in the range of 1:5-20. 3. The flare chamber according to claim 1, characterized in that the inner surface of the mixing chamber has the shape of a cylinder or prism. 4. The flare chamber according to claim 1, characterized in that the ratio of the maximum and minimum cross-sectional areas of the internal space of the compression chamber is within 3-5, and the ratio of the maximum length of the internal space of the compression chamber to the ratio of the said areas does not exceed 2. 5. The flare chamber according to claim 1, characterized in that the inner surface of the compression chamber has the shape of a truncated cone or a truncated pyramid. 6. The flare chamber according to claim 1, characterized in that the junction of the coolant supply system with the mixing chamber is located near the outlet of the flame tube.

Images