SU1740956A1 - Method of thermal-hydraulic stabilization of steam- generating channel - Google Patents

Abstract

Use: heat and power plants for various purposes. SUMMARY OF THE INVENTION: At the input single-phase section of the channel, the flow is simultaneously throttled and twisted by placing at the channel entrance a multi-worm screw with an unstressed input and a variable spin pitch. 1 il.

Description

The invention relates to energy and can be used in thermal power plants for various purposes.

A known technical solution is to install multiple-worm augers into the pipelines, which allow efficiently twisting the flow, giving it a rotational motion according to the law of a quasi-solid body. Spinning the flow allows intensifying heat transfer and at the same time eliminating hydraulic shocks, which are one of the causes of pipeline vibration. At the same time, this method of stabilizing the steam generating channel cannot ensure the achievement of the maximum effect, since it does not provide an increase in the supply of thermohydraulic stability due to the small pressure drop at the channel inlet. In addition, installing a swirler closer to the channel exit in this case destabilizes the heat exchange process, since the ratio of the pressure drop at the inlet

The (single phase) portion to the pressure drop across the two phase portion decreases.

Closest to the present invention is a method for stabilizing a steam generating channel by shaking it at the inlet. This method of stabilization effectively reduces the pulsations of the coolant in the channel and provides the necessary supply of thermal and hydraulic stability, but does not contribute to an increase in the intensification of heat transfer, but only is accompanied by additional energy costs for pumping the coolant. The lack of swirling flow at the channel inlet with this method of stabilization significantly reduces the practical value of the measures taken and does not allow simultaneously achieving an increase in the stock of thermal-hydraulic stability and the intensification of heat exchange.

The purpose of the invention is to increase the stock of thermo-hydraulic stability and the intensification of heat exchange.

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The goal is achieved by the fact that in the steam generating channel e containing the input single-phase and two-phase sections, in addition to throttling the flow at the input single-phase section, simultaneously with the throttling of the flow at the input section, it is twisted by placing at the entrance of the channel a multiple-feed screw with an impact-free inlet and variable spin pitch.

The method is carried out as follows.

A multiple screw with a variable pitch and an unstressed inlet is installed at the entrance to the NGV as a throttle element, for which purpose the gap is sealed along the line of contact between the auger vanes and the inner surface of the channel. The flow directed to the PGK acquires a pressure drop due to the acceleration and twisting. The pressure drop ensures the thermal-hydraulic stability of the channel. Twist intensifies heat transfer. The shock-free input provides a non-cavitation flow regime.

Due to the uneven resistance of the screw with a variable pitch in the forward and reverse direction, the stabilization of the channel is further improved due to greater isolation of the channel entrance from oscillatory processes originating in the channel. In addition to this, multiple swirls provide twist according to the law of quasi-solid rotation, unlike single-turn swirl or twisted tape, which have more developed secondary currents in the inter-blade channel, destabilizing the flow twist.

Due to the intense swirling of the flow, steam separation also occurs with the formation of the stability of a parabolic phase boundary, the unstable behavior of which, in the absence of centrifugal mass forces, is one of the reasons for the instability of the PGK.

The rotation and the acceleration of flow associated with it (due to the presence of the tangential component of the velocity) intensify the heat exchange already in the economizer section. Subsequently, in the evaporating section in the field of mass forces, the still small bubbles that are formed are forcibly evacuated to the central part of the channel, thus facilitating the access of liquid to the surface of the NGL, which additionally intensifies the heat exchange.

Simultaneously with the intensification of heat transfer, the necessary pressure drop is provided at the inlet section.

the steam-generating channel, which leads to the provision of a stock of thermal-hydraulic stability, i.e. stabilizes the heat and mass exchange process in ISC with a certain

a guarantee.

The drawing shows the proposed device.

In PGK 1, multiple-feed auger swirler 2 s is installed as the throttles.

shock-free entry and displaced pitch, while the gap 3 between the outer edge of the blades and the inner wall of the channel is sealed.

The device works as follows.

Submerged to boiling water enters the auger swirler, where it twists in the interblade channels as it moves, and the pressure differential required to ensure the stability of the channel is processed. The stream is then directed to the channel. In the field of mass forces, vapor bubbles tend to the center of the channel. The vapor-water interface is stabilized. Under the action of centrifugal forces, large bubbles are destroyed, the passage of which through the water-vapor interface is accompanied by significant pressure fluctuations. Sealing edges of the blades

Claims (1)

a swirler with a channel wall eliminates leakages between adjacent channels, reducing swirl efficiency and creating secondary flows that violate the law of quasi-solid rotation of the flow. Rotation of the flow in the economizer part of the ISC also increases the critical heat flux. The proposed method of thermo-hydraulic stabilization of NGL makes it possible to achieve an increase in the channel stability with simultaneous intensification of heat exchange, an increase in the critical heat flux and a decrease in power for pumping the heat transfer medium. The proposed method allows to significantly expand the modes of operation of Freight One. Invention Formula A method of thermohydraulic stabilization of a steam generating channel containing single-phase and two-phase sections by throttling the flow at the single-phase section, characterized in that, in order to increase the supply of thermal-hydraulic stability and heat exchange intensification, simultaneously with the throttling of the flow at the input section, it is twisted by placing on the entrance of the channel multiple screw with an unstressed input and variable spin pitch. /