RU2585902C2 - Tubular furnace - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: invention relates to tubular vertical furnace with coils, flue pipe with recuperative heat exchanger. Tubular furnace consists of furnace housing vertical lined with protective shell, chimney with recuperative heat exchanger, inside furnace housing is mounted several coiled or rectangular inner and outer coils of pipes located coaxially and forming between each other and annular beam reflective partition installed between coils channels for passage of flue gases formed during combustion of fuel from burner fixed in furnace hearth, characterised by that flue gas duct with recuperative heat exchanger, recuperator tube furnace is installed in parallel to furnace housing on foundation separate from furnace at distance from furnace union outlet to recuperator union inlet, equal to length of case controlled gate and the length of suction inlet union and is connected to lower part of the with diameter equal to that of casing installed inside pipe recuperator adjustable shutter and monitoring sensors measuring instruments, and outlet branch pipe of furnace is connected to space of furnace formed between external coil with minimum gaps between pipes and heat-resistant protective shell, lining of furnace housing, and inner coil outside is equipped with beam reflective shell with bandages stiffness at the ends secured via posts and brackets to bottom and cover of furnace, and in upper part of internal coil an adjustable flame deflector opposite exhaust valve on detachable cover of furnace, and recuperator in the lower part of tube space is equipped with inlet nozzle of smoke exhauster in lower part of its distribution chamber there are inlet and outlet unions with connecting pipe, connected at bottom with external convective coil, at top with internal radiant coil and at bottom with pipe and outlet union passing through hole in bottom or furnace housing to consumers of end product.

EFFECT: higher efficiency and reliability of furnace operation.

1 cl, 1 dwg

Description

The invention relates to a device for a tubular vertical furnace with coils, a chimney and can be used in the refining, petrochemical industry for the processing of petroleum products, chemical products and other products.

Known tube furnace (Patent RU No. 2385896, C1 04/10/2010), including a radiant coil, a reflective shell located between the lining of the furnace and the pipes of the radiant coil, and in the lower part of a separate convection chamber connected by a duct made of segment elements in the form of one and a half additionally installed coils connected to a hollow chimney, decreasing section to its upper part.

However, such a furnace arrangement has a number of significant disadvantages.

The connecting duct between the radiant and convective chambers passes from the top of the furnace down to the convection chamber located outside the furnace. This leads to additional heat loss to the environment and flue gas resistance. The gas duct is an extremely complex, material-intensive design consisting of segment elements and flange connections requiring sealing, with a safety valve on the gas duct (more often such valves are installed on the furnace lid).

Insufficient heat exchange surface of the radiant chamber, equipped with only one main food coil, and at the bottom of the furnace is equipped with additional coils for by-products. The furnace does not have a flap (valve) for starting and seasonal traction, a smoke exhauster, a flame arrester and places and the method of their fastening.

Known tube furnace (patent RU No. 2296926, C2 02/10/2007), including a lined housing, divided by an annular partition into a radiant and convective chamber with coils, ducts and a chimney. The furnace body in the upper part is made with a lid, a hatch and openings, into which pipes of convective and radiant coils are passed, connected to the outside of the furnace by flanges. The coils are mounted on sliding suspensions relative to the annular partition, and the chimney is mounted on the same base as the furnace body and is connected to the convection chamber by two symmetrically arranged ducts. This patent may be the prototype for the invention.

Disadvantages of this oven

A chimney installed on the same basis as the furnace is difficult to maintain when operating hazardous production facilities. With such a device of the furnace, it is impossible to install additional equipment (for example, an adjustable damper, smoke exhaust, sensors and control and measuring devices) and conduct its strapping and maintenance.

A chimney with a convection chamber is connected by two symmetrically arranged long ducts with many elbows, with much greater resistance of the flue gases when they enter the environment (atmosphere), it is much easier to connect directly with one short pipe. The furnace body in the upper part is made with a lid, a hatch and holes for convective and radiant coils connected by flanges outside the furnace. It is much easier to connect these coils inside the furnace itself by welding with one connecting pipe, which reduces the length of the connection and does not require sealing an additional eight flange joints with skirts for a high-temperature product. At the same time, in practice, installation, dismantling of the coils is ensured.

Installing a cover with a hatch in the center of the furnace body under the direct influence of a long straight torch from the nozzle of the gas burner can destroy the furnace cover, therefore, a flame absorber is needed at the top of the radiant coil, cutting the gas flow from the center of the furnace body to the periphery.

The external (convective) coil through the annular partition is mounted on sliding suspensions. It is most effective to fix this coil without sliding suspensions, by manufacturing this coil with a minimum gap between the pipes of this coil, which are supported by each other, which can further increase the heat transfer surface of the coil or significantly reduce the height of the furnace and the annular partition and, accordingly, reduce the metal consumption and cost of the furnace .

The aim of the invention is to eliminate the above drawbacks and increase the reliability of operation of the furnace, increase efficiency through the use of heat of flue gases, improve the environment, reduce costs and increase the efficiency of the furnace as a whole.

The problem is solved in that a chimney with a vertically mounted recuperative heat exchanger of a tubular furnace (hereinafter referred to as a recuperator) is installed parallel to the furnace body on a foundation separate from the furnace at a distance from the outlet nozzle of the furnace to the inlet of the recuperator, equal to the length of the adjustable damper body and the length of the inlet of the exhaust fan, and connected to the lower part of the furnace body by a nozzle with a diameter equal to the diameter of the heat exchanger casing, and an adjustable damper is installed inside the nozzle and sensors are used for monitoring instruments, and the furnace outlet pipe is connected to the furnace space formed between the external coil with minimal gaps between the pipes and the heat-resistant protective shell, the furnace shell lining, and the internal coil is equipped with a beam-reflecting shell outside, with stiffeners at the ends, fixed through racks and brackets to the furnace bottom and cover, and in the upper part of the internal coil there is an adjustable flame picker opposite the exhaust on the removable furnace cover, and a recuperator in the lower part of the annular space The equipment is equipped with an inlet nozzle from the smoke exhaust, and in the lower part of its distribution chamber, an inlet and outlet nozzles are installed with a connecting pipe connected in series to the bottom with an external convective coil, to the top with an internal radiant coil and to the bottom with a pipe and outlet fitting passing through an opening in the hearth or body ovens to consumers of the target product.

As a result of this technical solution, the optimal layout of the furnace is achieved, convenient reliable maintenance and operation of the furnace as a hazardous production facility is provided, it is possible to install additional equipment and the efficiency of the furnace as a whole. The design of the furnace is greatly simplified, the labor costs and resistance of the flue gases are reduced due to the connection of the convection chamber of the furnace with the chimney with a recuperative heat exchanger of the tube furnace with one short straight pipe and a short connection of convective and radiant coils due to welding inside the coils. Improved reliability of the tube furnace. To protect the furnace lid with a flange from premature destruction of the torch’s direct effect from the burner nozzles, including the presence and convenient installation of the exhaust valve, their protection is provided by means of an adjustable flame absorber that cuts direct flow from the center of the radiant chamber. An external convective coil due to its manufacture with a minimum clearance between the coil tubes (coil tubes may touch each other) does not require the installation of sliding suspensions, and at the same time, it significantly reduces the height of the beam reflector shell and increases the heat transfer surface.

The reflective heat-resistant shell, in addition to serving to heat the outer surface of the inner coil, plays the role of separating the radiant and convective chambers of the furnace, is fixed rigidly at the top and bottom of the furnace using bandages of stiffness, racks and brackets passing through the holes in the lid and bottom of the furnace. The recuperator in the lower part of the annular space is additionally equipped with an outlet fitting for connecting a smoke exhauster, necessary in case of seasonal draft change, depending on the ambient temperature and pressure, both in winter and summer time in different climatic zones. In the lower part of the recuperator distribution chamber, the inlet and outlet fittings with the connecting product pipe are connected in series with the furnace, at the bottom with the external convective coil, at the top with the internal radiant coil and at the bottom with the connecting pipe and outlet connecting through the hole in the hearth or the furnace body to the consumers target product (usually to a distillation column).

Flue gases pass through the annulus of the recuperator, the chimney with the head is gradually cooled at the outlet of the chimney (up to 300-350 ° C), which significantly improves the environmental situation in the furnace zone.

The furnace includes (Fig. 1) a vertical casing 1, a lining 2, a protective high-temperature heat-resistant steel shell 3, an automated gas burner 4 with a nozzle for spraying the burned fuel and an air pressurization system to ensure stable combustion in the furnace is attached most often to the furnace casing. In the upper part of the inner coil 7, an adjustable flame retardant 5 is installed, opposite the exhaust valve 6. Inside the furnace, several twisted cylindrical or rectangular coils 7, 8 are installed, separated by a special beam-reflecting shell 9. The radiant coil 7 is mounted at several points on the upper part with brackets 18 through an opening in a removable furnace cover 21. The coils are installed coaxially and form channels between themselves and the beam-reflecting shell for the passage of flue gases generated during the combustion of fuel using gas burner. At the bottom of the hearth of the furnace one or more peepers 10 are installed.

Between the convection chamber of the furnace 11 and the recuperative heat exchanger 12, a connecting pipe 13 is installed, in which an adjustable gate valve 14 is installed. An inlet pipe of a smoke exhaust fan 15 with a valve (or plug) is cut into the connecting pipe 16. An inlet fitting 17 is installed in the annulus of the heat exchanger, connected by a pipe 23 , with outlet fitting of the exhaust fan. The upper part of the chimney 19 is equipped with a head 20, contributing to the discharge of the gas stream when it enters the atmosphere. An outlet fitting is installed in the pipe space of the recuperator, connected by a pipe 24 to the entrance to the external coil 8.

The work of the invention.

The initial product enters from below into the inlet fitting of the recuperator tube space, heats up due to the flue gases to a predetermined temperature and enters into the outlet from the recuperator, and through the connecting pipe 24, it sequentially enters the external coil of furnace 8 from the bottom, then into the internal coil of furnace 7 from top to bottom and through the connecting pipe 23 to the outlet nozzle of the furnace to consumers.

The product is heated in the furnace by burning fuel with the help of a special burner with a nozzle in a radiant chamber with a beam-reflecting shell with the formation of radiant energy and high-temperature flue gases entering the convection chamber and through a connecting pipe 13, an adjustable damper 14 (or, if necessary, a smoke exhauster) to annulus of recuperator and chimney. When the smoke exhaust valve 14 closes.

The flow of high temperature flue gases (with a temperature of about 800 ° C), passing successively the space of each coaxial furnace coil, a recuperator, chimney, head, enters the environment. Flue gases passing through the annular space of the recuperative heat exchanger heat the product in the pipe space and are cooled at the outlet of the chimney to a temperature of ≈300-400 ° C, which significantly improves the environmental situation in the furnace zone.

INFORMATION SOURCES

1. Patent RU 2364810 C1, dated 11.03.2008, IPC F28D.

2. Patent RU 2385896 C1, dated July 17, 2008, IPC C10G 9/20.

3. Patent RU 2296926 C2, dated March 17, 2004, IPC F27B 5/00, C10G 9/20.

Claims (1)

A tube furnace containing a vertically mounted furnace shell lined with a protective shell, a lid with a hatch and openings, an inlet and outlet pipe of the furnace, a chimney with a vertically mounted recuperator with inlet and outlet fittings, several internal radiant and external convective pipe coils are mounted inside the furnace body, located coaxially and forming between themselves and the annular partition installed between the coils, channels for the passage of flue gases generated during fuel combustion, burners fixed in the hearth of the furnace, the inlet and outlet nozzles of the coils, characterized in that it is equipped with a smoke exhauster with inlet and outlet nozzles, a beam-reflecting shell with stiffeners at the ends, fixed outside the inner coil through racks and brackets to the hearth and the cover of the furnace, made removable, and an adjustable flame eliminator located in the upper part of the internal coil opposite the exhaust valve on the removable cover of the furnace, while the chimney with a recuperator is installed parallel to the furnace body, separate from the furnace and is connected to the lower part of the furnace body by a pipe, inside which an adjustable damper and sensors of control and measuring instruments are installed, with a diameter equal to the diameter of the recuperator casing, while the distance from the furnace output pipe to the recuperator inlet is equal to the length of the adjustable damper body and the length of the inlet of the smoke exhauster , the outlet pipe of the furnace is connected to the space of the furnace formed between the outer coil with minimal gaps between the pipes and the heat-resistant protective shell of the lining the furnace body, the recuperator in the lower part of the annular space is equipped with an inlet fitting for connecting the smoke exhauster, and in the lower part of its distribution chamber, the inlet and outlet fittings are installed with a connecting pipe connected in series with the external convective coil at the bottom, with the internal radiant coil at the top and with the pipe at the bottom and an outlet fitting passing through an opening in a hearth or furnace body.

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