System for recovering heat of continuous blow-down water of boiler
By designing a system for continuous sewage discharge heat recovery of boiler, using the ring structure and third valve control method, the problem of unused sewage discharge heat of boiler is solved, heat recovery and waste heat utilization are realized, and energy consumption is reduced. Land cost.
Patent Information
- Application Number
- CN202420543398.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-20
- Publication Date
- 2025-02-18
- Estimated Expiration
- 2034-03-20
AI Technical Summary
In the prior art, the heat of continuous sewage discharged by boilers has not been effectively recycled, resulting in a large amount of high-quality energy being discharged in vain, and the drainage pool covers a large area and has high civil engineering costs.
A system for continuous sewage discharge heat recovery of boiler is designed. By connecting the heating heat user and the water mixing unit in parallel to form a ring structure, connecting the continuous sewage discharge expansion container and the regular sewage discharge expansion container, the third valve is used to control the circulation structure. The sewage is turned on and off, achieving heat recovery and waste heat utilization.
Fully recycle and utilize the heat from the high-temperature water discharged by the boiler, reduce energy consumption of conventional heating systems, reduce tap water consumption, and reduce land occupation and civil engineering costs.
Smart Images
Figure CN222503815U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of heat recovery in power plants, and in particular relates to a system for recovering heat from continuous sewage discharge from boilers. Background Art
[0002] The feed water entering the boiler drum contains a certain amount of salt. After the boiler is treated with chemicals, the scaling substances in the boiler water are converted into slag. In addition, the corrosion of metals by boiler water will also produce some corrosion products. Therefore, there are various soluble and insoluble impurities in the boiler water. During the operation of the boiler, only a small part of these impurities are taken away by steam, and most of them remain in the boiler water. As the boiler water continues to evaporate, the concentration of these impurities gradually increases. Excessive concentration of impurities in the boiler water not only affects the quality of steam, but also causes scaling and corrosion of the heating surface, affecting the safe operation of the boiler. In order to control the quality of boiler water, supercritical units ensure the quality of steam water by controlling the quality of boiler water, while subcritical units discharge the boiler to discharge part of the boiler water contaminated by salt and slag, and supplement it with demineralized water. The purpose of continuous boiler blowdown is to discharge part of the salt dissolved in the boiler water to maintain a certain salt content and alkalinity of the boiler water. This blowdown is continuously discharged from the evaporation surface where the salt concentration of the boiler water is the highest.
[0003] The amount of water discharged from the continuous sewage of the boiler is continuous and stable. The water temperature in the continuous sewage expansion tank is about 160℃. The continuous sewage expansion tank is connected to the periodic sewage expansion tank. When the water in the continuous sewage expansion tank reaches a certain liquid level, the valve between the continuous sewage expansion tank and the periodic sewage expansion tank opens, and the pressure of the continuous sewage expansion tank drops rapidly. Due to unstable pressure, when the pressure in the sewage expansion tank is low, the waste heat and waste heat utilization system needs to add a pressurizing device such as a water pump to overcome the internal resistance of the waste heat and waste heat utilization system. If the increased pump head is too small, it will not meet the system resistance requirements. If the increased pump head is too large, when the pressure in the sewage expansion tank increases, the system working pressure is too large, causing system overpressure, which may cause damage to equipment and pipelines. Due to the limitation of technical level, the original means of utilizing the continuous sewage of the boiler are few and not fully utilized. Usually, the continuous sewage of the boiler is discharged from the bottom of the boiler drum into the continuous sewage expansion tank. The continuous blowdown from the boiler is saturated water under the working pressure of the boiler, with high temperature and large enthalpy. If its pressure is suddenly reduced, the vaporization point of the water is reduced, the original saturated state is destroyed, part of the water releases superheated heat to become saturated water under the new pressure, and part of the water absorbs the latent heat of evaporation and becomes steam. This evaporation is called flash evaporation. The continuous blowdown expansion tank uses the principle of flash evaporation to obtain secondary steam. The boiler blowdown with certain parameters is suddenly input from the pipeline into an expansion tank with a volume several times larger than the pipeline. The pressure is reduced and the volume is increased, so that steam is flash evaporated. The continuous blowdown expansion tank is connected to the boiler blowdown port to reduce the pressure and expand the continuous blowdown of the boiler. The blowdown is adiabatically expanded in the continuous blowdown expansion tank to separate into secondary steam and waste hot water, and is expanded, depressurized, mixed with normal temperature water and cooled in the expansion tank, and then discharged through the drainage tank. It is estimated that for every 1% increase in the blowdown rate, the fuel consumption will increase by about 0.3%. Usually, the sewage discharge rate of low-pressure and small-capacity boilers is controlled at 5% to 10%; for medium and high-pressure boilers, the sewage discharge rate of condensing power plants using desalted water as make-up water is no more than 1%; the sewage discharge rate of condensing power plants using softened water as make-up water is no more than 2%; the sewage discharge rate of thermal power plants using desalted water as make-up water is no more than 2%; the sewage discharge rate of thermal power plants using softened water as make-up water is no more than 5%. In summary, boiler sewage is discharged in vain, wasting a lot of high-quality energy.
[0004] Therefore, the existing technology currently has the disadvantages that the heat of boiler sewage is not reasonably recovered and utilized, the drainage pool occupies a large area and the civil construction cost is high. Utility Model Content
[0005] In order to solve the technical problems existing in the prior art, the utility model provides a system for recovering heat from continuous sewage discharge from a boiler.
[0006] The technical solution of the utility model is to provide a system for heat recovery of continuous sewage discharge from a boiler, comprising a continuous sewage discharge expansion tank and a periodic sewage discharge expansion tank connected and arranged, wherein a sewage inlet is arranged on the continuous sewage discharge expansion tank, and the periodic sewage discharge expansion tank is connected to a fixed drainage tank;
[0007] A first valve is connected to the continuous sewage expansion container;
[0008] A second valve is connected to the first regulating valve, the second valve is connected to the continuous blowdown expansion tank, and the first regulating valve is connected to the periodic blowdown expansion tank; and
[0009] A heating heat user and a water mixing unit are connected to the continuous sewage expansion tank. The heating heat user and the water mixing unit are arranged in parallel and connected to the periodic sewage expansion tank through a third valve.
[0010] Furthermore, the water mixing unit includes a second regulating valve, a third regulating valve, a check valve, a water mixing pump and a fourth valve connected in sequence, the second regulating valve is connected to the continuous sewage expansion tank, and the fourth valve is connected to the third valve.
[0011] Compared with the prior art, the utility model provides a system for continuous boiler sewage heat recovery, which has the following beneficial effects:
[0012] The utility model forms a ring structure by connecting the heating heat user and the water mixing unit in parallel, and one side of the ring structure is connected to the continuous sewage expansion tank for water inlet, and the other side of the ring structure is connected to the periodic sewage expansion tank through the third valve for water outlet. The heating heat user and the water mixing unit form a circulation structure, and the third valve can control the sewage after circulation in the structure to be on and off to the periodic sewage expansion tank, so as to fully recycle and utilize the heat of the boiler sewage high-temperature water, and use the recovered waste heat for winter building heating through reasonable means, thereby reducing the energy consumption of the conventional heating system; the hot waste water after waste heat recovery has a lower water temperature, and the amount of mixed normal temperature water can be reduced accordingly, reducing the water consumption of the original system tap water. At the same time, because the circulating water volume of the heating system and the system water capacity of the conventional heating system are reduced, the consumption of softened water replenishment of the conventional heating system can be reduced; because the original mixed water volume is reduced, the total water volume is correspondingly reduced, which can effectively reduce the volume of the water tank required by the original system, thereby reducing the land occupation and civil engineering costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 The utility model is a schematic diagram of a system for recovering heat from continuous sewage discharge from a boiler. DETAILED DESCRIPTION
[0014] The specific implementation of the present utility model is described in detail below in conjunction with specific embodiments.
[0015] like Figure 1 As shown, a system for heat recovery of continuous sewage discharge from a boiler is provided, comprising a continuous sewage discharge expansion tank 100 and a periodic sewage discharge expansion tank 101 which are connected and arranged, a sewage inlet is arranged on the continuous sewage discharge expansion tank 100, the periodic sewage discharge expansion tank 101 is connected to a fixed drainage tank 102, a first valve 103 located at a steam discharge outlet is connected and arranged with the continuous sewage discharge expansion tank 100, when the system is started, the first valve 103 is opened first to discharge the steam in the continuous sewage discharge expansion tank 100 to reduce its internal pressure. A second valve 104 is connected and arranged with a first regulating valve 105, the second valve 104 is connected with the continuous sewage discharge expansion tank 100, the first regulating valve 105 is connected with the periodic sewage discharge expansion tank 101, the second valve 104 is used to control the on-off of sewage in the pipeline between the continuous sewage discharge expansion tank 100 and the periodic sewage discharge expansion tank 101, and the first regulating valve 105 is used to control the flow rate of the water flow. The heating heat user 106 and the water mixing unit 107 are arranged in parallel to form an annular structure and one side is connected to the continuous sewage expansion tank 100 for water intake, and the other side of the annular structure is connected to the periodic sewage expansion tank 101 through the third valve 108 for water discharge. The heating heat user 106 and the water mixing unit 107 form a circulation structure, and the third valve 108 can control the flow of sewage circulated in the structure to the periodic sewage expansion tank 101.
[0016] Specifically, the water mixing unit 107 includes a second regulating valve 109, a third regulating valve 110, a check valve 111, a water mixing pump 112 and a fourth valve 113 connected in sequence. The second regulating valve 109 is used to adjust the flow rate of sewage flowing into the water mixing unit 107, the third regulating valve 110 is used to adjust the flow rate of the mixed sewage after passing through the water mixing unit 107, the check valve 111 is used to keep the mixed sewage in a single flow direction and cannot flow in the reverse direction, which is a counterclockwise flow in this embodiment. The water mixing pump 112 is used to mix cold water and sewage and pump them out, and the fourth valve 113 is used to control the flow of water flowing into the water mixing pump 112.
[0017] An embodiment is provided, which is to install 2 sets of 1100MW-class combined cycle heating units, including 2 gas turbine generator sets, 2 waste heat boilers, and 2 steam turbine power generation and heating units (extraction back pressure steam turbines). The boiler drum discharge water is about 167°C and the pressure is about 0.65MPa. The discharge water of a single unit is 3t / h, and the discharge water of two units is 6t / h in total. After waste heat utilization, the outlet water temperature is 70°C. A water supply pressurized water mixing unit 107 is used. After mixing, the outlet water on the low temperature side is consistent with the original factory area heating water temperature of 95°C, and the return water is 70°C. According to the formula, the mixing ratio is 2.88. In order to avoid insufficient water supply pressure, a water supply pressurized water mixing unit 107 is used with a flow rate of 1.6m 3 / h, head 20m. Equipped with 2 hot water pumps, one for use and one for backup, water pump flow 5.8m 3 / h, head 22.1m, speed 2900r / min, cavitation margin 0.6m, power 2.2kW, equipped with control cabinet, valves, thermometer, pressure gauge, etc., primary water supply 167℃, return water 70℃, secondary water supply 95℃, secondary water return 70℃.
[0018] The working principle of this system is as follows:
[0019] The heating water supply is taken from the pipeline before the second valve 104 between the boiler drum continuous blowdown expansion tank 100 and the fixed drainage blowdown expansion tank. The water temperature is about 160℃, the pressure is about 0.65MPa, and the water quality is the same as that of the boiler water. The low-temperature water after heat recovery by the heating heat user 106 is discharged to the pipeline after the last valve between the continuous blowdown expansion tank 100 and the fixed drainage blowdown expansion tank, or directly discharged into the fixed drainage blowdown expansion tank. During operation, first open the first valve 103 of the steam outlet of the continuous blowdown expansion tank 100, and then slowly open the fifth valve at the sewage inlet. At this time, the equipment slowly enters the operating state until the flow reaches the normal sewage discharge volume. At this time, the water level in the continuous blowdown expansion tank 100 gradually rises. When reaching the normal water level, open the second regulating valve 109, the third regulating valve 110, the third valve 108, the fourth valve 113, the fifth valve and the mixing pump 112. The water supply temperature of the heating system is adjusted by adjusting the second regulating valve 109, the third regulating valve 110 and the mixing pump 112. The water level in the continuous sewage expansion tank 100 is divided into normal water level, high water level and low water level. When the load of the heating heat user 106 decreases, the opening of the second regulating valve 109 is gradually reduced, and the opening of the third regulating valve 110 is increased. At this time, the water level in the continuous sewage expansion tank 100 gradually increases. When the high water level alarm signal is triggered, the second valve 104 is normally open, and the opening of the first regulating valve 105 is opened and gradually increased through the interlock. At this time, the water level in the continuous sewage expansion tank 100 begins to drop until the water level reaches the low water level, and then the opening of the first regulating valve 105 is gradually reduced until it is closed.
[0020] The utility model fully recycles and utilizes the heat of the high-temperature water discharged from the boiler, and uses the recovered waste heat for heating buildings in winter through reasonable means, reducing the energy consumption of the conventional heating system; the hot waste water after waste heat recovery has a lower water temperature, which can reduce the amount of mixed normal temperature water and reduce the tap water consumption of the original system. At the same time, because the circulating water volume of the heating system and the system water capacity of the conventional heating system are reduced, the consumption of softened water replenishment of the conventional heating system can be reduced; because the original mixed water volume is reduced, the total water volume is reduced accordingly, which can effectively reduce the volume of the water tank required by the original system, thereby reducing land occupation and civil engineering costs.
Claims
1. A system for heat recovery of continuous wastewater from boilers, characterized in that: It includes a continuous sewage expansion container and a periodic sewage expansion container which are connected and arranged, wherein the continuous sewage expansion container is provided with a sewage inlet, and the periodic sewage expansion container is connected with a fixed drainage tank; A first valve is connected to the continuous sewage expansion container; A second valve is connected to the first regulating valve, the second valve is connected to the continuous blowdown expansion tank, and the first regulating valve is connected to the periodic blowdown expansion tank; and A heating heat user and a water mixing unit are connected to the continuous sewage expansion tank. The heating heat user and the water mixing unit are arranged in parallel and connected to the periodic sewage expansion tank through a third valve.
2. A system for heat recovery of continuous boiler wastewater as claimed in claim 1, characterized in that: The water mixing unit comprises a second regulating valve, a third regulating valve, a check valve, a water mixing pump and a fourth valve which are connected in sequence, the second regulating valve is connected to the continuous sewage expansion container, and the fourth valve is connected to the third valve.