A method for anti-freezing control of an intercooling system

Abstract

The application provides an anti-freezing control method for an indirect cooling system, characterized in that the water filling sequence of the cooling triangular sectors of the indirect air cooling tower is in a clockwise direction, the water filling mode adopts interval sector water filling, and each sector is filled with water once and then ends. The application can make the temperature field distribution of the indirect cooling island more uniform, effectively avoid the phenomenon that the temperature of the cooling triangular sector which is not filled with water is low, improve the anti-freezing capacity of the indirect air cooling tower, and improve the safety and economy of the power plant.

Description

Technical Field

[0001] This invention relates to the field of indirect air cooling technology, and in particular to a method for preventing freezing in indirect cooling systems. Background Technology

[0002] In an indirect air-cooled system, the air-cooled tube bundle (also known as the "cooling triangle") is placed vertically at the bottom of the cooling tower. Air flows outside the tube bundle, while cooling water cools the tube bundle inside. Louvers are installed at the bottom of the cooling tower to regulate airflow. The circulating water inside the finned tubes of the radiator in an indirect air-cooled system is prone to freezing, which can cause the tube bundle to burst. Repairing frozen radiators is technically challenging, labor-intensive, and results in significant losses. Therefore, to use indirect air-cooled systems in cold regions, it is essential to address the issue of winter freeze protection for the radiators.

[0003] The control of the indirect air-cooled tower cooling system is integrated into the unit's DCS control system. The indirect cooling system mainly has three types of control: temperature control, pressure control, and water level control. Among them, water level control is to ensure the appropriate water level in the expansion tank and underground water tank during the start-up phase of the cooling system, and to ensure the water filling of the sector and the normal operation of the cooling system.

[0004] Taking a cooling tower with six heat exchange sectors evenly distributed within the tower as an example, namely sector #1, sector #2, sector #3, sector #4, sector #5, and sector #6, each sector consists of 22 cooling triangles arranged vertically around the perimeter of the cooling tower. In traditional operation and control methods, depending on the target back pressure of the unit, the water filling operation and control sequence of the cooling triangle sectors is sector #1, sector #2, sector #3, sector #4, sector #5, and sector #6. Since the diameter of indirect air-cooled towers is generally over 150 meters, this operation and control logic can easily lead to uneven temperature field distribution in the indirect cooling island, resulting in lower temperatures in the unfilled cooling triangle sectors, which increases the risk of freezing in the indirect cooling island.

[0005] Therefore, a new operation and control method that is beneficial for preventing the unit from freezing is needed. Summary of the Invention

[0006] The purpose of this invention is to provide an operation control method that can make the temperature field distribution of the indirect cooling island more uniform, effectively avoid the phenomenon of excessively low temperature in the uncooled triangular sector of the indirect cooling island, and improve the antifreeze capability of the indirect cooling island.

[0007] This invention provides a method for antifreeze control of an indirect air-cooled system. The water filling sequence of the cooling triangular sector of the indirect air-cooled tower is clockwise, and the water filling method adopts intermittent sector water filling, with each sector completing one water filling before the process ends.

[0008] Furthermore, the water filling sequence starts with odd-numbered sectors. After the odd-numbered sectors are filled, the even-numbered sectors are then filled.

[0009] Furthermore, the water filling order for odd-numbered sectors is from smallest to largest.

[0010] Furthermore, after the first sector to begin water filling is completed, if the unit's back pressure has not reached the set target value and the conditions for filling the next sector are met, then the next sector is allowed to begin water filling.

[0011] Furthermore, the water filling sequence starts with even-numbered sectors. After the even-numbered sectors are filled, the odd-numbered sectors are then filled.

[0012] Furthermore, the water filling order for even-numbered sectors is from smallest to largest.

[0013] Furthermore, after the first sector to begin water filling is completed, if the unit's back pressure has not reached the set target value and the conditions for filling the next sector are met, then the next sector is allowed to begin water filling.

[0014] Furthermore, the cooling triangular sector of the indirect air-cooled tower includes several sectors.

[0015] The beneficial effects of this invention are: it effectively avoids the phenomenon of low temperature in the cooling triangular sector without water filling, improves the antifreeze capability of the indirect air-cooled tower, facilitates the achievement of the back pressure control target of the power plant, and improves the safety and economy of the unit. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is the control logic diagram for the water filling operation of sector #3 of this invention;

[0018] Figure 2 This is the control logic diagram for the water filling operation of sector #5 of the present invention. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] like Figure 1 and Figure 2 As shown, this invention provides a method for anti-freezing control of an indirect air-cooled system. The water filling sequence of the cooling triangular sectors of the indirect air-cooled tower is clockwise, and the water filling method employs intermittent sector filling. The water filling sequence starts with odd-numbered sectors; after the odd-numbered sectors are filled, the even-numbered sectors are filled next. The water filling sequence of odd-numbered sectors is from smallest to largest. After the first sector to begin filling is completed, if the unit's back pressure has not reached the set target value, and the conditions for filling the next sector are met, then the next sector is allowed to begin filling.

[0023] The condition that a sector is ready for water filling is defined as the simultaneous fulfillment of the following conditions:

[0024] The expansion tank level is equal to or higher than the set level.

[0025] The electric drain valve at the outlet of the water pump and the electric overflow valve of the expansion tank are closed, while the electric water filling valve at the outlet of the water pump is opened.

[0026] The motorized blinds in this sector are closed; and

[0027] The electric drain valve for this sector is closed.

[0028] Suppose an indirect air-cooled tower has 6 cooling triangular sectors. The water filling sequence for these sectors is clockwise, alternating between sectors #1, #3, and #5 (odd-numbered sectors, from smallest to largest), followed by sectors #2, #4, and #6 (even-numbered sectors, from smallest to largest). This is not the traditional clockwise sequence of sector #1, #2, #3, #4, #5, and #6.

[0029] In some preferred embodiments, the water filling sequence begins with even-numbered sectors. After the even-numbered sectors are filled, the odd-numbered sectors are then filled. The water filling sequence for even-numbered sectors is from smallest to largest. After the first sector to be filled is completed, if the unit's back pressure has not reached the set target value, and the conditions for filling the next sector are met, then the next sector is allowed to begin filling.

[0030] In some preferred embodiments, the cooling triangular sector of the indirect air-cooled tower comprises several sectors. Suppose an indirect air-cooled tower has six cooling triangular sectors; then the water filling sequence of the corresponding cooling triangular sectors is clockwise and alternates, i.e., cooling triangular sector #2, cooling triangular sector #4, and cooling triangular sector #6, starting with the even-numbered sectors from smallest to largest, followed by cooling triangular sector #1, cooling triangular sector #3, and cooling triangular sector #5, i.e., the odd-numbered sectors from smallest to largest. This is not the traditional clockwise sequential order of #1, #2, #3, #4, #5, and #6.

[0031] This water filling control logic for the cooling triangular sector can make the temperature field distribution of the indirect cooling island more uniform, effectively avoid the phenomenon of low temperature in the unfilled cooling triangular sector, improve the antifreeze capability of the indirect air-cooled tower, and improve the safety and economy of the power plant.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preventing freezing in an intercooling system, characterized in that, The cooling triangular sector of the indirect air-cooled tower includes several sectors. The water filling sequence of the cooling triangular sector of the indirect air-cooled tower is clockwise. The water filling method adopts intermittent sector water filling. Each sector is filled once and then the filling ends. After the first sector to start water filling is completed, if the unit's back pressure has not reached the set target value and the conditions for filling the next sector are met, then the next sector is allowed to start water filling.

2. The antifreeze control method for an intercooling system according to claim 1, characterized in that, The water filling sequence starts with odd-numbered sectors. After the odd-numbered sectors are filled, the even-numbered sectors are then filled.

3. The antifreeze control method for an intercooling system according to claim 2, characterized in that, The odd-numbered sectors are filled with water in ascending order.

4. The antifreeze control method for an intercooling system according to claim 1, characterized in that, The water filling sequence starts with even-numbered sectors. After the even-numbered sectors are filled, the odd-numbered sectors are then filled.

5. The antifreeze control method for an intercooling system according to claim 4, characterized in that, The even-numbered sectors are filled with water in ascending order.

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