SU1315496A2 - Method for heating large-size hollow metal weldments - Google Patents

Abstract

The invention relates to the production technology of chemical and petroleum equipment, as well as hollow metal welded products working under pressure, and is an improvement of the invention according to A.S. No. 1002377. The purpose of the invention is to increase the heating uniformity of the forming product by reducing heat loss. The method consists in applying a thermal insulation layer of variable thickness to the outer surface of the product, with minimum thickness at the entrance to the product cavity at the maximum temperature section, and the greatest thickness of thermal insulation layer at the output of the cavity. The thickness of & I, the layer of thermal insulation is determined by the formula 3-} 1G,. where nts - product height, 2 tab., 1 sludge. (L with ate 4 :: X 35 14)

Description

The invention relates to the technology of manufacturing chemical and petroleum equipment, as well as hollow metal welded products, working under pressure and requiring volume heating with various types of heat treatment, and is an improvement of the method according to the author. St. No. 1002377.

The aim of the invention is to increase the uniformity of heating over the generator, by reducing heat losses.

The drawing shows a device that implements the proposed method

The method is carried out as follows.

Thermal insulation 2 is applied to the outer surface 1 of the product. In the area Z-zone, at the entrance to the product cavity, where the maximum heat supply is applied, thermal insulation is applied with a minimum thickness. This is due to the fact that in this place the most intense heat exchange is observed, since the coolant has a maximum speed and temperature, rapid heating of the product walls occurs.

With distance from zone 3 in the direction of the heat transfer medium, the thickness of the thermal insulation layer increases to a maximum, depending on the height of the heated product. The maximum thickness of the layer of heat insulation is applied to the roof of 4 products (top bottom) up to the throttle 5, through which the heat carrier is ejected.

Increasing the thickness of the heat insulating layer is necessary to reduce heat loss, since as the heat transfer medium inside the product moves, its speed and temperature decrease, and consequently, the intensity of heating of the product walls decreases.

The application of thermal insulation of variable thickness to the outer surface of the product ensures uniform heating by reducing temperature differences between the upper part of the product and the lower and radial gradient.

Example. To determine the uniformity of heating on the forming product, two columns of size 30000x7000x70, which are made of two-layer steel, are used.

Heat treatment is performed in assembly conditions in autumn at a temperature of

environment + 5 ° C during the rain and strong northwest wind.

Thermal insulation of a uniform layer thickness of 150 mm along the entire height (length) of a mineral wool column is applied to the outer surface of a vertically installed column 1.

Thermal insulation of a variable layer thickness is applied to the outer surface of a vertically installed column 2 in accordance with the formula.

SH

On the surface of the heated columns, 22 thermocouples are fixed to - take readings of the heating temperature at various points on the surface.

As a criterion of uniformity of heating, temperature differences in height between the opposite ends of the column (bTR) and the diameter of the column (TTR) are taken, opposite points in the cross section of the diameter.

The change in the thickness of the heat insulating layer according to the formula is shown in Table. one.

Heat insulation thickness at the top

the bottom of the column 25 ,. 500 mm and H

 fc (matr)

 30,000 mm applied to the throttles with a partial girth.

The results of measurements of the values of y.Tts and Ltd are given in table 2. I

As can be seen from the table. 2, the use of thermal insulation of variable thickness leads to a reduction in the unevenness of the temperature distribution during the entire heating cycle. The obtained LT value on column 2 is two times less than on column 1. The difference in diameter also decreases significantly.

It should be noted that in order to obtain a δTC: 50 ° C difference in the case of heat treatment of the t column, it is necessary to further increase the duration of exposure, which required a higher standard consumption of gaseous fuel.

Therefore, to increase the equal. the number of heating during heat treatment from inside is necessary to apply insulation of variable thickness according to the formula Ots

 EVIL

The use of the invention will reduce the time duration

313 heat treatment process and gaseous fuel consumption.

Formula of invention

Method of heating, large-sized hollow metal welded products according to ed. St. No. 1002377, about tl and h ayu y and so that, in order to increase the uniformity of heating on the forming product by reducing heat losses, on the outer surface

Heat insulation in real conditions of the experiment.

about where h

54964

the product is pre-coated with a thermal insulation layer of variable thickness in height, while the thickness of the layer with increasing distance from the entrance to the cavity

- products to exit it are increased and determined by the formula

n s4nG

 - height of the heated product 5 Oi - thickness of heat insulation i

Table 1

T + g-atm -

TZ2- M

TP-T.

22

 ff, -500tin

Hk-20,0i bc chuonn

And by 15.0 hours fOOfTff

.OM fn JOOftn

, 0n bn-uopp

Editor H, Gunko

Compiled by G. Nazarov

Tehred M. Khodanich Proofreader S. Shekmar

Order 2318/27 Circulation 549 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

Claims (1)

Claim The method of heating. Large-sized hollow metal welded products according to ed. St. No. 1002377, which implies that, in order to increase the uniformity of heating along the generatrix of the product by reducing heat loss, a layer of thermal insulation of a variable thickness is preliminarily applied to the external surface of the product, while the thickness of the layer as it moves away from the entrance to the cavity 5 of the product to the exit from it is increased and determined by the formula -. v zK 10 where N _to - the height of the heated product; - thickness of thermal insulation * Table 1 mm | 1000 10,000 15,000 20000 J 3000 mm 95 300 367 424 525 eleven x 1 ; eleven eleven eleven mm * 100 300 350 400 500 * Thermal insulation thickness in real experiment conditions. table 2 Temperature measurement time after the start of heating, h Column Temperature difference ° C Conditions in height (ΔΤ _β ) diameter Ut _d ) 10 1 170 25 Wind rain 2 83 Yu Tatm - ⁺ 3 ° C thirty 1 . 100 10 T _atm - 2 ° C 2 60 10 38 1 70 •10 Wind 2 42 '. 5 T + 2 ° C 42 1 45 7 Wind T _atm + s ° s fa Ta-Thh 51 Nk'SCHon ί _η -500in Tp-T _yy l · 1 -g Ηκ-ΖΟ, Οη bn ^ W ^ Opm Tu-T _t6 ΊΊ / t * ΊΟ and j Nk-15.0n Vi * ChOOnts Tg-tfo ; // No. 10.0n 0k ~ OOOnn : Bj ^± 0.00 τ, -τ _ζ Hk * 1.0n 0n * YuO ηη Compiled by G. Nazarov Editor N. Gunko Tehred M. Khodanich Corrector S. Shekmar Order 2318/27 Circulation 549 Subscription VNIIIPI of the USSR State Committee for Inventions and Discoveries 113035, Moscow, Zh-35, Raushskaya nab., D. 4/5 Production and printing company, Uzhhorod, st. Project, 4