Vertical multiple passage drainable heated surfaces with headers-equalizers and forced circulation

Abstract

The present invention discloses improved heated surfaces (HS) with vertical multiple passage panels or vertical serpentine coils from straight tubes with connections between them by top and bottom bends. In HS with tube bends there is not any mixing headers—each circuit has a single tube from inlet header to outlet header. This increases mass velocity of flow and improves stability and temperature regulation of tubes. The bottom bends have holes. The bottom bend holes of the adjacent passes are connected with drain header by drain stubs. Each header serves to drain the adjacent tube passes and as equalizing header of pressure / flow. It will help to decrease multivaluedness and maldistribution of flow between parallel tubes of the module. Such design of HS noticeably decreases the corrosion of tubes.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application claims priority to U.S. provisional application No. 62 / 062,055 filed on Oct. 9, 2014.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention is the heated surfaces (HS) for application in the different technical fields—power industry, metallurgy, chemical industry, etc. Below the invention is considered in the context of power industry.[0004]2. Background Art[0005]For units of power industry which are based on Brayton and Rankine cycles the general tendency is increasing, the initial parameters—pressure and temperature to improve, the thermal efficiency (TE) and decrease carbon dioxide emissions. In the modern conventional units the pressure is well above the critical pressure. The boilers of such units are once through type.[0006]The same tendency with pressure increasing can be seen in the case of Combine Cycle Power Plants (CCPP) as well. At present time the pressure in steam genera...

AI Technical Summary

Benefits of technology

[0009]In HS with tube bends there are not any mixing headers—each circuit goes like a single tube from inlet header to outlet header. It allows increasing mass velocity of steam / water or steam-water mixture for subcritical pressure (or supercritical fluid) and improves stability of flow and temperature regime of tubes.

[0010]To have opportunity for water drain at the lower point of bottom bends there are the holes. The bend holes of the adjacent passes are connected with drain header by pipe stubs. Each header serves for drain of the adjacent tube passes. At the same time the header can serve as equalizing header of pressure / flow. In the case of the different thermal-hydraulic characteristics of parallel tubes there is opportunity for bypass flows. It will help to decrease multivaluedness and maldistribution of flow between parallel tubes of the module. Besides such design of HS noticeably decreases the corrosion when the units are not in operation.

Problems solved by technology

Besides such design of HS noticeably decreases the corrosion when the units are not in operation.

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