RU2235253C2 - Plenum-exhaust air duct making method - Google Patents

Abstract

FIELD: nuclear, chemical, mining and biological industries; ventilation facilities.

SUBSTANCE: invention can be used for transportation of vapor-gas-air mixtures containing harmful and dangerous components from isolated rooms. According to proposed method of making plenum-exhaust air duct system consisting of plenum and exhaust air ducts including straights and different connecting parts, members, supports and suspensions, all parts and connections of inner exhaust air duct members are welded and feature high gas tightness, and those of outer plenum air exposed to higher pressure are seamed, welded, flanged or nipple design, their assembling is carried out, in steps successively starting from one end of main part of air duct.

EFFECT: enlarged operating capabilities, possibility of ventilating isolated rooms where harmful and dangerous substances liberated in process of operation of equipment are present.

4 dwg

Description

The invention relates to a ventilation technique and can be used to move steam-gas mixtures containing hazardous components in a number of areas with harmful emissions from enterprises in the nuclear, chemical, mining and biological industries.

A known method of making the supply and exhaust duct containing the supply and exhaust ducts, consisting of straight sections and various connecting parts, elements, supports and suspensions (SU 964367 A, 10/07/1982).

The disadvantages of the prototype is the lack of tightness of individual links and connections of the ducts, which determines their use only in general ventilation systems for livestock buildings with the aim of sanitary air exchange with maximum savings in heat costs, as well as the lack of information on the method of their installation.

The technical task of the proposed duct is to expand its use for ventilation of isolated rooms (boxes, chambers) with harmful and hazardous emissions from process equipment. The technical solution is achieved by creating a sealed design of the exhaust pipe-type exhaust duct, which ensures, first of all, high radiation, chemical or bacteriological safety due to the pressure difference in the supply and exhaust channels, the implementation of the regenerative heating of the supply cold air and the development of a rational way to make the combination exhaust system.

The technical result is achieved in that the method of making the supply and exhaust duct containing the supply and exhaust ducts, consisting of straight sections and various connecting parts, elements, supports and suspensions, consists in the fact that the parts and connections of the elements of the internal exhaust duct are only welded with high gas density, and the external supply air duct, which is under higher pressure, folded, welded, flanged or nipple, and their assembly is performed in steps o and sequentially from one end of the main part of the duct.

The invention is illustrated by drawings, where figure 1 shows a conditional diagram of the trace of the main part of the supply and exhaust duct; figure 2 shows its cross section; Figures 3 and 4 show the assembly order by the welding method of adjacent duct links.

The supply and exhaust duct contains an external 1 and an internal 2 ducts located concentrically to each other along the entire length of the highway. The outer circular duct consists of straight sections 2000-6000 mm long and parts for them: bends 3 and half bends 4, branch nodes (tees and crosses) 5, silencers 6, external horizontal 7 and vertical 8 supports and suspensions. The circular circular internal duct does not have silencers, but has internal sliding supports 9, and the branch nodes can be located at its end sections outside the main part of the duct. If the flow velocities are equal, the cross sections of the inner and outer channels are determined by a ratio of diameters of 1.4: 1, and with a certain excess of the flow velocity in the annular channel, the outer diameter becomes less than 1.4 of the inner diameter, which leads to a decrease in metal consumption and air duct weight. The straight sections of the external and internal ducts should be the same length, reaching 2000-6000 mm. The horizontal and vertical straight sections of the circular circular inner duct 1 rest on semicircular ribbed inner supports made of a steel strip and welded to their outer surface at a distance of at least 200 mm from the ends, and if necessary, a third - similar median support can be used.

All links of the internal duct are made of sheet, preferably stainless, 1-3 mm thick straight welded steel with high gas density, and their butt joints during installation are made only by welding. The links of the external duct can be made of thinner sheet, preferably galvanized, steel longitudinal welded seam or welded, and their connections can be not only welded, but also flanged or nipple. The assembly of the links of the main part of the supply and exhaust duct is carried out stepwise and sequentially from one end thereof, when the initial section of the external duct 1 is fixed to in the outer support 7, and the portion of the internal duct 2 is extended by 50-100 mm and brought to its end extended to the same the length of section 2 of the adjacent link, then their welded joint 1 is performed, the quality of the seam is monitored, if necessary, the coil is cut out for laboratory analysis and a new coil is welded. After this, the section 1 of the adjacent link of the external duct is approaching and a welded, flanged or nipple connection 11 is made. Successively, in the same order, the following various links of the duct are mounted, and the bends 3 of the internal duct are easily inserted into two half-outlets 4 of the external duct, after which the latter are connected.

The supply and exhaust duct is used as follows. Harmful and dangerous vapor-gas mixture is taken from an isolated room and transported through an internal exhaust duct through a gas purifier to a ventilation pipe or shaft with a roof fan. Fresh supply air enters the supply chamber, equipped with pressure fans, filters, check valves and control devices, from where it is transported along the annular section of the external duct and through the branch unit 5 enters the air vents of the ventilated room. Silencers 6 installed on the highway reduce the level of aerodynamic noise. With increased excess pressure of the supply air in the annular cross-section of the external duct and lower pressure (vacuum) in the internal exhaust duct, hazardous mixtures do not leak, even in case of emergency depressurization of the latter. The countercurrent flow direction leads to efficient regenerative heat transfer through the wall of the internal duct.

Thus, the task is solved by concentric placement of air ducts with the formation of an annular flow of supply air and the possibility of their mutual displacement on internal supports during installation. Creating a pressure difference in the flows increases the gas tightness of the connections of the internal exhaust duct, guaranteeing reliable radiation, chemical or bacteriological safety when transporting gas-vapor mixtures from isolated rooms. The countercurrent flows creates an efficient recuperative heat transfer, and the method of stepwise sequential assembly of the supply and exhaust duct elements is simple and practically feasible.

Claims (1)

A method of making a supply and exhaust duct containing a supply and exhaust ducts, consisting of straight sections and various connecting parts, elements, supports and suspensions, characterized in that the parts and connections of the elements of the internal exhaust duct are made only welded with high gas density, and the external supply duct being under higher pressure - folded, welded, flanged or nipple, and their assembly is carried out stepwise and sequentially, starting from one end and the main part of the duct.

Images