A deaerator feed water return system

Abstract

The present invention relates to a deaerator feedwater reflux system, which comprises a feedwater preheater, a feedwater pump, a deaerator, a boiler feedwater pump, a coal economizer and a boiler connected in sequence, wherein the feedwater preheater is cyclically connected to a circulating pump, a heat exchanger and a condensate tank through a bypass pipeline, and the heat exchanger heats cold water into hot water for domestic use. Compared with the prior art, the present invention can avoid water hammer or air blockage in the water flowing from the feedwater preheater to the deaerator, thereby improving the safety of boiler operation; and at the same time improving the utilization rate of heat.

Description

Technical Field

[0001] The invention relates to the technical field of boilers, and in particular to a deaerator feedwater reflux system. Background Art

[0002] A boiler is an energy conversion device. The energy input to the boiler includes chemical energy and electrical energy in the fuel. The boiler outputs steam, high-temperature water or organic heat carrier with a certain amount of thermal energy. The boiler water inlet system usually includes a deaerator and an economizer. Among them, the deaerator is used to remove oxygen and other gases dissolved in the feed water, prevent and reduce the corrosion of the boiler feed water pipe, economizer and other auxiliary equipment; the economizer is a heat exchanger that uses the waste heat of the boiler exhaust to heat the feed water. As the feed water entering the drum passes through the economizer, the water temperature is increased, reducing the thermal stress of the drum wall caused by the temperature difference, thereby improving the working conditions of the drum and extending the service life of the drum.

[0003] The connection of the existing boiler feed water system is as follows Figure 1 As shown, the purified water is pumped into the feed water preheater 1, and after preheating, it is pumped into the deaerator 3 through the feed water pump 2 for deoxygenation, and then pumped into the economizer 5 by the boiler feed water pump 4. Since the water inlet of the deaerator is started and stopped irregularly according to the liquid level of the deaerator, and the feed water preheater is continuously fed with water, this causes the temperature of the feed water entering the deaerator to be high and low at times, which is prone to water hammer and feed water vapor blockage. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a deaerator feed water return system which is more stable and has higher heat utilization rate.

[0005] The purpose of the present invention can be achieved by the following technical scheme: a deaerator feedwater reflux system, the system includes a feedwater preheater, a feedwater pump, a deaerator, a boiler feedwater pump, an economizer and a boiler connected in sequence, the feedwater preheater is cyclically connected to a circulating pump, a heat exchanger and a condensate tank through a bypass pipeline, and the heat exchanger heats cold water into hot water for domestic use. The present invention timely takes away the heat in the feedwater preheater by setting a bypass pipeline, so that the water temperature in the feedwater preheater remains constant, avoiding the generation of water hammer and feedwater vapor resistance. In addition, the heat in the feedwater preheater can be fully utilized.

[0006] The heat exchanger is a shell and tube heat exchanger, whose tube side water inlet is connected to the circulation pump, the tube side water outlet is connected to the condensate tank, the shell side water inlet is connected to cold water, and the shell side water outlet is connected to the domestic hot water user.

[0007] A No. 1 solenoid valve is provided on the connecting pipeline between the water supply pump and the water supply preheater, and a No. 2 solenoid valve is provided on the connecting pipeline between the circulation pump and the water supply preheater. The No. 1 solenoid valve and the No. 2 solenoid valve are opened alternately.

[0008] The system is provided with a controller, and the controller is connected to the No. 1 solenoid valve and the No. 2 solenoid valve. The deaerator is provided with a liquid level sensor, and the liquid level sensor is connected to the controller. The present invention controls the switch of the No. 1 solenoid valve and the No. 2 solenoid valve through the liquid level sensor and the controller, so as to realize the flow direction of water in the feed water preheater. When the water level in the deaerator is too low, the liquid level sensor gives a signal, and the controller controls the No. 1 solenoid valve to open, and the water in the feed water preheater flows to the deaerator through the feed water pump until the liquid level in the deaerator reaches the upper limit, at which time, the No. 2 solenoid switch is closed. When the liquid level in the deaerator reaches the upper limit, the liquid level sensor gives a signal, and the controller controls the No. 1 solenoid valve to disconnect and the No. 2 solenoid valve to open, so that the heat in the feed water preheater flows to domestic hot water.

[0009] Preferably, the controller is a PLC controller.

[0010] The flue gas of the boiler is discharged after passing through the economizer and the feed water preheater in sequence. This design enables the heat of the boiler flue gas to be fully utilized.

[0011] Compared with the prior art, the beneficial effects of the present invention are embodied in the following aspects:

[0012] (1) Avoid water hammer or vapor lock in the water flowing from the feedwater preheater to the deaerator, thereby improving the safety of boiler operation;

[0013] (2) Improve the utilization rate of heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the existing boiler water inlet connection;

[0015] Figure 2 It is a schematic diagram of the boiler water inlet connection of the present invention.

[0016] Among them, 1 is a feed water preheater, 2 is a feed water pump, 3 is a deaerator, 4 is a boiler feed water pump, 5 is an economizer, 6 is a boiler, 7 is a circulating pump, 8 is a heat exchanger, 9 is a condensate tank, 10 is a controller, 11 is a solenoid valve No. 1, and 12 is a solenoid valve No. 2. DETAILED DESCRIPTION

[0017] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0018] Example 1

[0019] A deaerator 3 water return system, the process of which is as follows Figure 2As shown, it includes a feed water preheater 1, a feed water pump 2, a deaerator 3, a boiler feed water pump 4, an economizer 5 and a boiler 6 connected in sequence. The feed water preheater 1 is cyclically connected to a circulating pump 7, a heat exchanger 8 and a condensate tank 9 through a bypass pipeline. The heat exchanger 8 heats cold water into hot water for domestic use.

[0020] The heat exchanger 8 is a shell and tube heat exchanger, whose tube-side water inlet is connected to the circulation pump 7, the tube-side water outlet is connected to the condensate tank 9, the shell-side water inlet is connected to cold water, and the shell-side water outlet is connected to the domestic hot water user.

[0021] A No. 1 solenoid valve 11 is provided on the connecting pipeline between the water supply pump 2 and the water supply preheater 1, and a No. 2 solenoid valve 12 is provided on the connecting pipeline between the circulation pump 7 and the water supply preheater 1. The No. 1 solenoid valve 11 and the No. 2 solenoid valve 12 are opened alternately.

[0022] The system is provided with a PLC controller 10, which is connected to the No. 1 solenoid valve 11 and the No. 2 solenoid valve 12. A liquid level sensor is provided in the deaerator 3, which is connected to the PLC controller 10. The switch of the No. 1 solenoid valve 11 and the No. 2 solenoid valve 12 is controlled by the liquid level sensor and the PLC controller 10, so as to realize the flow direction of water in the feed water preheater 1. When the water level in the deaerator 3 is too low, the liquid level sensor gives a signal, the PLC controller 10 controls the No. 1 solenoid valve 11 to open, and the water in the feed water preheater 1 flows to the deaerator 3 through the feed water pump 2 until the liquid level in the deaerator 3 reaches the upper limit, at which time, the No. 2 solenoid switch is closed. When the liquid level in the deaerator 3 reaches the upper limit, the liquid level sensor gives a signal, the PLC controller 10 controls the No. 1 solenoid valve 11 to disconnect, and the No. 2 solenoid valve 12 to open, so that the heat in the feed water preheater 1 flows to the domestic hot water.

[0023] The flue gas of the boiler is discharged after passing through the economizer 5 and the feed water preheater 1 in sequence. This design makes full use of the heat of the boiler flue gas.

Claims

1. A deaerator feedwater return system, the system comprising a feedwater preheater, a feedwater pump, a deaerator, a boiler feedwater pump, an economizer and a boiler connected in sequence, characterized in that: The feed water preheater is cyclically connected to a circulation pump, a heat exchanger and a condensate tank through a bypass pipeline, and the heat exchanger heats cold water into hot water for domestic use; The heat exchanger is a shell and tube heat exchanger, the tube side water inlet is connected to the circulation pump, the tube side water outlet is connected to the condensate tank, the shell side water inlet is connected to cold water, and the shell side water outlet is connected to the domestic hot water user; A No. 1 solenoid valve is provided on the connecting pipeline between the water supply pump and the water supply preheater, and a No. 2 solenoid valve is provided on the connecting pipeline between the circulation pump and the water supply preheater, and the No. 1 solenoid valve and the No. 2 solenoid valve are opened alternately; The system is provided with a controller, and the controller is connected with a No. 1 solenoid valve and a No. 2 solenoid valve. A liquid level sensor is provided in the deaerator, and the liquid level sensor is connected with the controller.

2. A deaerator feed water return system according to claim 1, characterized in that: The controller is a PLC controller.

3. A deaerator feed water return system according to claim 1, characterized in that: The flue gas of the boiler is discharged after passing through the economizer and the feed water preheater in sequence.

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