RU222074U1 - HEAT GENERATOR FOR BAKERY ROTARY OVEN - Google Patents

Abstract

The utility model relates to the design of a heat generator for a baking rotary oven. In a heat generator of a baking rotary oven, containing a burner placed in a casing of rectangular cross-section, connected to a flame tube communicated with tube bundles with a staggered arrangement of heat exchange tubes, on the side walls of the casing along the entire length of the intertube space at the level of each row of tubes in places where the gap between the tubes expands The bundle and the casing are equipped with horizontal deflectors, and the distance from the center of the tube to the deflector is 0.7 of the distance between the centers of the tubes along the flow front, while guides in the form of inclined shelves are installed on the side walls of the casing above the bundle of tubes at an angle α = 30° to the side wall of the casing. Technical result: increased heat transfer intensity and increased heat transfer.

Description

The utility model relates to the design of a heat generator for a baking rotary oven.

Baking and confectionery rotary ovens using gas and liquid fuel are widely known. In such leaks, heat generators are used that combine a combustion chamber and a heat exchanger.

A well-known heat generator for a baking rotary oven (“ROTATIONAL BAKERY OVEN”, utility model patent No. 18313, MPK A21B 1/00, 2018), adopted as a prototype, with a heat exchanger made with coolant flows opposite to each other. The specified heat generator contains a gas burner, a casing of rectangular cross-section with a flame tube (combustion chamber) communicated with s-shaped tube bundles and a staggered arrangement of heat exchange tubes. The heated air enters the casing from below, where the tubes have the lowest temperature. Then it circulates upward between the tubes, where the temperature is high, the heated air washes around the flame tube.

The disadvantages of this heat exchanger are reduced heat transfer due to uneven flow around the heat exchange tubes in the center of the casing and at its side walls, as well as in the zone of the flame tube.

The technical result that the claimed utility model is aimed at achieving is increasing the intensity of heat transfer and increasing heat transfer.

The technical result is achieved by the fact that in the heat generator of a baking rotary oven, containing a burner placed in a casing of rectangular cross-section, connected to a flame tube communicated with tube bundles with a staggered arrangement of heat exchange tubes, on the side walls of the casing along the entire length of the inter-tube space at the level of each row of tubes in In places where the gap between the tube bundle and the casing expands, horizontal deflectors are installed, and the distance from the center of the tube to the deflector is 0.7 of the distance between the centers of the tubes along the flow front, while on the side walls of the casing above the tube bundle, guides are installed in the form of inclined shelves under angle α=30° to the side wall of the casing.

The essence of the utility model is illustrated by the drawing, in Fig. 1 shows a schematic representation of a heat generator, and Fig. 2 - cross section of the heat generator.

The heat generator of a baking rotary oven contains a casing 1 of rectangular cross-section. In the upper part of the casing 1 there is a burner 2 with a flame tube 3 communicated with the staggered heat exchange tubes 4. On the side walls of the casing 1 along the entire length of the inter-tube space at the level of each row of tubes 4 in places where the gap between the tube bundle and casing 1 widens, deflectors are installed 5 in the form of horizontal shelves. The distance from the center of the tube to the deflector is 0.7⋅s, where s is the distance between the centers of the tubes along the flow front. Deflectors 5 provide local turbulence, leading to turbulence of the coolant flow near the walls, which in turn leads to an increase in heat transfer. On the side walls of the casing 1 above the bundle of tubes, guides 6 are installed in the form of inclined shelves at an angle α=30° to the side wall of the casing 1, ensuring the directed movement of the heated coolant to improve the flow around the flame tube.

The heat generator of a baking rotary oven works as follows.

In a baking rotary oven, hot air for baking is obtained by burning gas in a gas burner 2 of a heat generator and transferring heat using a heat exchanger through an air duct into the baking chamber. From the gas burner 2, hot exhaust air is directed into the flame tube 3. The exhaust flue gases move inside the bundle of heat exchange tubes 4 and are removed through the flue gas outlet pipe 7. To transport hot flue gases from the burner 2 to the chimney, for example, s-shaped tubes are used, it is also possible to use straight tubes 4 in combination with rotary manifolds 8 located inside the casing 1 (Fig. 1). The heated air circulating in the baking chamber enters the casing 1 from below, where the heat exchange tubes 4 have the lowest temperature. The heated air moves in the inter-tube space, washing the heat exchange tubes 4, heading upward, where the temperature of the tubes is high. At the side walls of the casing 1, deflectors 5 provide local turbulence, leading to turbulization of the flow and its direction into the tube bundle, which leads to intensified heat transfer and increased heat transfer. Guides 6 in the form of inclined shelves on the side walls of the casing 1 above the bundle of tubes 4 ensure the directed movement of the heated coolant around the flame tube 3, increasing heat transfer. The distance from the center of the tube to the deflector (0.7 from the distance between the centers of the tubes along the flow front) and the angle of inclination (α=30°) of the guides 6 in the form of inclined shelves, ensuring the achievement of the technical result, were obtained by numerical modeling.

Thus, in comparison with the prototype, the inventive heat generator provides an increase in heat transfer intensity and an increase in heat transfer. Together with the enterprise OJSC Yartorgtekhnika, an experimental sample of a heat generator for a baking rotary oven with the following characteristics was manufactured and tested: thermal power 50 kW, dimensions (L × H × W) 700 × 400 × 170 mm, weight 45 kg, type of heat exchange part - recuperative tubular two-pass heat exchanger, combustion chamber (flame tube) - hexagonal pipe. Based on the test results, the manufactured experimental sample showed the performance of the proposed design. During the experiments, the heat generator worked with a diesel burner in the PKKH-1 rotary baking oven. During the tests, the surface temperatures of the heat exchange tubes of the heat generator, the air temperature inside the furnace and the fuel consumption of a diesel burner were measured. To measure temperatures, THC Chromel-Kopel thermocouples were used with a measured temperature range from 200 to 800°C. The measurement error according to the passport is ±1.5°C. The test results of the proposed device confirmed the improvement in the intensification of the heat transfer process of the heat generator and the improvement in thermal characteristics.

Claims (1)

Heat generator for a baking rotary oven, containing a burner placed in a casing of a rectangular cross-section, connected to a flame tube communicated with tube bundles with a staggered arrangement of heat exchange tubes, characterized in that on the side walls of the casing along the entire length of the inter-tube space at the level of each row of tubes in places where the gap expands Between the tube bundle and the casing, deflectors are installed in the form of horizontal shelves, and the distance from the center of the tube to the deflector is 0.7 of the distance between the centers of the tubes along the flow front, while guides in the form of inclined shelves at an angle α are installed on the side walls of the casing above the tube bundle =30° to the side wall of the casing.

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