MXPA97001257A - Assembly of sector plate and seal for three-section air pre-heater - Google Patents

Abstract

The present invention relates to seal assembly for a rotary regenerative three-sector air heater including a rotor housing, a rotor located in the rotor housing having a plurality of radially extending diaphragms that form compartments in the rotor and having radial seals that extend over the axial edges of the diaphragms and also include sector plates at both axial ends of the air pre-heater that divide the pre-heater of air into a sector of combustion gas, a sector of primary air and a sector of secondary air, the mojoras is characterized because it includes plates of sector between combustion gas and the primary air sectors and between the sector of combustion gas and the sector of secondary air that is of a size to be in coupling with two of the radial seals at all times and a sector plate between the sectors of primary and secondary air that is of a size p To be in coupling only with one of the radial seals at any particular time

Description

ASSEMBLY OF SECTOR PLATE AND SEAL FOR PRE-HEATER "- AIR OF THREE SECTORS BACKGROUND OF THE INVENTION The present invention relates to regenerative, rotary, three-sector air heaters that employ double radial seals and more particularly to assembly and sizing of the plates of sectors that divide the pre-heater in the three sectors.The burning of pulverized coal is the most commonly used procedure to burn coal in large steam generators, such as steam generators of public services. pulverized coal typically uses air to dry, sort and transport the coal to the sprayer, air to the sprayer is referred to as the primary air, while the remaining combustion air is referred to as secondary air. that the ignition is carried out and this drying is achieved by the use of hot primary air that then tr Bring the pulverized coal dry to the kiln. The pre-heater of three sectors is used in large boilers that operate with coal, particularly where a cold primary air fan is suitable. The pre-heater is designed in such a way that by dividing the air side of the pre-heater into two sectors, the primary air of higher pressure can be heated along with the secondary air in a single r '* -heat heater. It is well known to provide seal means in air pre-heaters to prevent mixing of the combustion gases with air. These may include axial seals around the outer periphery of the rotor, between the rotor and the housing and radial seals that extend over the upper and lower edges of the radially extending separations that form the compartments in the rotor. The radial seal member on the edges of the separations cleans against the sector plates that divide the pre-heater of air into sectors for gas and air. The coupling of these radial seals with the sector plates minimizes leakage and the mixing of gas and air. In order to keep the leak as low as practicable, it is common to provide a double seal assembly. In this arrangement, the sector plates are equal in size to two rotor compartments, such that the radial seals in two rotor compartment separations, which extend radially consecutively (diaphragms), are in engagement with the sector plate. at the same time. This contrasts with a single seal assembly where the sector plates only need to be equal in size to one compartment. The problem with a double seal assembly is that sector plates occupy or block a significant percentage of the flow area through the pre-heater. Each plate of sector of double seal b *. That the double of the area of flow that a plate of sector of simple stamp. That means that the pressure drop through the pre-heater increases or that the size needs to be increased. COMPENDIUM OF THE INVENTION The present invention relates to a three-sector air pre-heater, which includes double radial seals between the gas and air sectors but only single radial seals between the primary and secondary air sectors. More particularly, the sector plates between the gas sector and the two air sectors are equal in size to two rotor compartments, thereby providing double seals while the sector plate between the primary and secondary air sectors are only equal in size to a compartment, thus providing a simple seal. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagrammatic representation of an air pre-heater system with three sectors and sprayer. Figure 2 is a general perspective view of a rotary three-sector regenerative air heater that is sectioned to show the upper sector plates.

Figure 3 is a simplified representation of an air preheater with three sectors of the prior art having double radial seals. Figure 4 is a representation similar to Figure 3, but illustrating the sector plate assembly of the present invention. Figure 5 is a cross-sectional view of a portion of a sector and rotor plate illustrating a double seal assembly. Figure 6 is a plan view of a portion of an air preheater illustrating an axial seal assembly. DESCRIPTION OF THE PREFERRED EMBODIMENT Figure 1 of the drawings shows the general arrangement of a coal sprayer 12, in combination with a three-sector air pre-heater 14. The coal is fed to the sprayer 12 from the supply line 16 and the pulverized coal is fed to the carbon nozzles of a generator steam (not shown) through lines 18. The combustion gas from the steam generator is fed to the air pre-heater 14 through the pipeline 20 after which the cooled combustion gas is fed to the chimney. The primary combustion air is blown into the air pre-heater 14 by the blower 22 and at least a portion of this primary air is fed through the air pre-heater 14 into one of the sections where it is heated by the air. combustion gas. The primary air heated in the duct 24 can be mixed with unheated primary air from the duct 26, to produce a final primary air stream in the duct 28 which is fed to the sprayer 12. This primary air dries the coal, aids in sorting the carbon fines in the sprayer and transports the coal fines to the steam generator. The secondary combustion air is fed to another sector of the air pre-heater by the blower 30, where it is heated by the combustion gas and then fed directly to the steam generator. This is the conventional way of arranging and operating a three-sector air pre-heater in combination with a carbon atomizer and steam generator Figure 2 is a perspective view of an air pre-heater 14 constructed According to the present invention, the air pre-heater 14 comprises a rotor housing 32 in which the rotor 34 is mounted. As is conventional, the rotor contains a mass of thermo-exchange elements which absorbs the heat of the combustion gas stream 36 and transfers that heat to the intake air stream 38. The rotation of the rotor 34 is indicated by the arrow 40. The internal components of the rotor 34 are not illustrated in this Figure 2 in order to show more clearly the invention but will include the radial separations or diaphragms, which form the compartments for the elements of ter ointerca bio and the radial seals that will be explained below.

The rotor housing 32 is divided into three sectors p '• the sector plates 42, 44 and 46. Corresponding sector plates are on the bottom side of the rotor 34. The three sectors are the combustion gas sector 48, the primary air sector 50 and secondary air sector 52. Hot combustion gas 36 is directed to sector 48 via connection duct 54 (partially broken apart in the drawing), flows down through sector 48 and transfers heat to the thermal transfer surface in the rotor compartments and then circulate outward through the pipe connector 56. Since this hot heat transfer surface then rotates through the primary and secondary air sectors 50 and 52, the heat transfers to the air entering through the secondary air inlet duct connector 58 and the primary air inlet duct connector 59 (see Figure 1) to form a hot primary air stream 60 and in the pipe connector section 62, and a hot secondary air stream '4 in the pipe connector section 66. Figures 3 and 4 are plan view representations of an air pre-heater and housing rotor illustrating the sector plates in relation to radial seals and rotor. Figure 3 illustrates the sector plates according to the prior art, while Figure 4 illustrates the present invention. These Figures illustrate sector plates in cross section. The separations or diaphragms 68 divide the rotor into the compartments 70 that contain the heat-sensing surface that is usually available in modules adapted to fit within the compartments. Connected to the upper and bottom edges of these diaphragms are the radial seals 72 which are illustrated in cross section in Figure 5. This Figure 5 illustrates the double seal assembly wherein the sector plate 44 is sufficiently large, so that which extends over two compartments in such a way that two radial seals 72 are always in engagement with the sector plate as the rotor rotates. This can also be seen in Figure 3 where each of the sector plates 42, 44 and 46 of the prior art are of the same size and extend over two compartments. However, according to the present invention as illustrated in Figure 4, the sector plate 46 between the primary air sector 50 and the secondary air sector 52 is smaller and extends only one compartment in such a way that only a radial seal 72 is in contact with the sector lacquer 46 at any particular time. The reason for using a double radial seal assembly is to reduce leakage between sectors. When double radial seals are provided in pre-heaters of three sectors to reduce leakage, it is sometimes difficult to meet the requirements for low pressure drop of primary and secondary air due to the flow that is blocked by large sector plates. size. In the present invention, one of the sector plates 46 is smaller, providing this area with more air flow through the rotor and less pressure drop. The main interest with the leak is between the air and combustion gas sides of the air preheater. Some increased leakage between primary and secondary air can be easily tolerated. In this invention, the double seals between the combustion gas sector and the two air sectors are maintained. As an example, a three-sector air pre-heater with a 50 ° primary air sector will have a 25% to 30% reduction in primary air pressure drop when using a 10 ° primary sector plate 46, instead of a sector plate of 20 °. Although leakage between the primary and secondary air sectors is not as critical as leakage between the air sectors and the combustion gas sector and even though the present invention will tend to increase leakage between the primary and secondary air sectors, it is still convenient to keep this leak * - >; a minimum. One way that can be realized is by maintaining the double axial seal between the primary and secondary air sectors instead of converting it into a single axial seal assembly, in conjunction with the conversion of the radial seal assembly. This is illustrated in Figure 6 which shows a plan view of a portion of an air pre-heater illustrating the housing 32, the rotor 34, the diaphragms 68 and the sector plates 44 and 46. Mounted inside the housing 32 are axial seal plates 74 and 76 (only two of the axial seal plates are illustrated) that extend the entire height of the rotor. Mounted on the rotor are axial seals 78 which are the same or similar to the radial seals 72. These axial seals 78 couple the axial seal plates, as the rotor rotates as radial seals couple the sector plates. While the sector plate 46 between the primary and secondary air sectors is reduced in size to extend only one compartment according to the present invention, the corresponding axial seal plate 76 can be maintained at double seal size as illustrated, so that two axial seal members always extend.

Claims (2)

1. CLAIMS 1.- Seal assembly for a rotary regenerative three-sector pre-heater that includes a rotor housing, a rotor located in the rotor housing that has a plurality of radially extending diaphragms that form compartments in the rotor and that they have radial seals that extend over the axial edges of the diaphragms and also include sector plates on both axial ends of the air pre-heater that divide the pre-heater of air into a sector of combustion gas, a sector of primary air and a secondary air sector, the improvement is characterized in that it comprises sector plates between the combustion gas sector and the primary air sectors and between the combustion gas sector and the secondary air sector which is of a t? to be in coupling with two of the radial seals at all times and a sector plate between the primary and secondary air sectors which is of a size to be in ^ - :: Opulation only with one of the radial seals at any particular time.
2. 2. Seal assembly as described in claim 1, characterized in that it also includes axial seals spaced around the outside of the rotor and axial seal plates connected to the interior of the rotor housing between the sectors for coupling with the axial seals and where each of the axial seal plates of a size to be e * coupling with two of the axial seals at all times.