CN108087862A - A waste steam waste heat recovery system for a fixed row expansion vessel and a deaerator - Google Patents

Abstract

The invention relates to a dead steam waste heat recovery system of a fixed-row flash tank and a deaerator, which comprises the fixed-row flash tank, an injection mixing heater, a heat exchanger and the deaerator which are sequentially connected, wherein the injection mixing heater is connected with a water supply pipe for supplementing softened water; the fixed-row flash tank is connected with an injection mixing heater through a steam discharge pipe; the fixed-row flash tank is connected with a flue gas desulfurization system. Compared with the prior art, the exhaust steam of the deaerator is sent to the heat exchanger to further heat the hot water heated in the injection mixing heater, and then the hot water heated in the heat exchanger enters the deaerator, so that the heat and the water generated by the fixed discharge flash tank are recycled, the heat and the working medium of the deaerator are well recycled, the heat economy of a power plant is improved, and the purposes of energy conservation and consumption reduction are achieved.

Description

A waste steam waste heat recovery system for a fixed row expansion vessel and a deaerator

technical field

The invention relates to the technical field of waste heat recovery and utilization, in particular to a system for recovering waste heat from waste steam of a fixed row expansion vessel and a deaerator.

Background technique

At present, for the drum boiler, during the operation of the unit, the pot water will continue to concentrate with continuous evaporation, and the salt content in the pot water will become higher and higher with the evaporation of the pot water. When the salt content reaches a certain concentration, the boiler water will produce foam, co-elevation of steam and water will occur, and the humidity of the steam will be greatly increased. In severe cases, a large amount of water will be carried in the steam, causing the boiler to shut down due to low water level. Under the existing boiler equipment and technical conditions, in order to ensure the safety of the boiler and the quality of externally supplied steam, the water quality of the boiler water must meet the standard requirements. Therefore, blowdown must be carried out when the boiler is running, and the same amount of feed water must be added.

The blowdown method is divided into continuous blowdown and regular blowdown, so most boilers are equipped with regular blowdown expander and continuous blowdown expander. Among them, the continuous discharge of boiler sewage is first expanded through continuous row expansion vessels, and the secondary exhaust steam generated enters the deaerator, and the water is drained and self-flowed to the fixed row expansion vessels for secondary flash expansion. In addition, steam drains for boiler auxiliary use, emergency water release from boiler drums, soot blowing drains, and valve leakage also enter the fixed-row expansion vessel. Discharge to the sky, causing a certain impact on the environment. The amount of exhaust steam in the fixed-discharge expansion vessel of the boiler is about 4t/h, which also causes a large amount of loss of working fluid and heat. The condensed water and winter steam heating and draining are directly imported into the fixed-discharge pool and enter the rain discharge of the factory area. At the same time, the boiler has zero meters The exhaust heat of steam heating and drainage and deaerator is not recovered, resulting in waste of water resources and heat sources. If the above low-pressure steam can be recovered and utilized, the fuel consumption of the boiler can be effectively reduced, thereby improving the economical efficiency of the boiler operation.

During the operation of the deaerator, in order to discharge the oxygen precipitated from the deaerator water, a part of the steam will also be discharged. According to the design and operation data of the deaerator, about 1-3kg of steam can be discharged per ton of deaerator water. Taking a 300MW unit as an example, the deaerator will discharge 2 tons of steam per hour. If this part of waste heat steam can also be recovered, 900 tons of standard coal can be saved every year, which is converted into about 500,000 yuan, and the waste caused by steam exhaust can also be eliminated. environmental pollution.

Contents of the invention

The object of the present invention is to provide a waste steam and waste heat recovery system for fixed row expansion vessels and deaerators in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions:

A system for recovering waste steam and waste heat of a fixed row expansion vessel and a deaerator, including a fixed row expansion vessel, an injection mixed heater, a heat exchanger, and a deaerator connected in sequence, and the injection mixed heater is connected for supplementary Water supply pipe for softened water.

Preferably, the fixed row expander is connected to the injection mixing heater through a steam discharge pipe.

Preferably, the fixed row expansion vessel is connected to a flue gas desulfurization system.

Preferably, the heat exchanger is a surface heat exchanger.

Preferably, a water pump is provided on the water supply pipe.

Preferably, the outlet of the water pump is provided with an electric regulating valve.

Preferably, the deaerator is connected to the heat exchanger through an exhaust pipe and a water inlet pipe.

Compared with the prior art, the present invention has the following advantages:

1. The exhaust steam from the deaerator is sent to the heat exchanger to further heat the hot water heated in the injection mixed heater, and then the heated hot water in the heat exchanger enters the deaerator, so that the fixed The heat and water generated by the expansion vessel are recycled and utilized, and the heat and working medium of the deaerator are also recycled and utilized, which improves the thermal economy of the power plant and achieves the purpose of saving energy and reducing consumption.

2. After the fixed-row sewage and various high-temperature hydrophobic water entering the fixed-row expansion vessel are flashed in the fixed-row expansion vessel, part of it becomes clean steam, and the remaining water has a higher alkalinity. When the water is discharged to the flue gas desulfurization system, not only heat and working fluid are recovered, but also because this part of the water contains high concentrations of phosphate and alkalinity, it can prevent internal corrosion of the hot water pipe network, and is more conducive to flue gas desulfurization.

3. The condensed water from the injection mixed heater is further introduced into the surface heat exchanger for heating, which further increases the water temperature and also recovers the heat of the deaerator.

Description of drawings

Fig. 1 is a schematic diagram of the device structure of the present invention.

Markings in the figure: 1. Fixed discharge expansion vessel, 2. Injection mixed heater, 3. Surface heat exchanger, 4. Deaerator, 5. Water pump, 6. Steam discharge pipe, 7. Outlet pipe, 8. Water inlet pipe, 9, exhaust pipe, 10, flue gas desulfurization system.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is carried out on the premise of the technical solution of the present invention, and detailed implementation and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

Example

A fixed row expansion vessel and deaerator exhaust steam waste heat recovery system, including fixed row expansion vessel 1, injection mixed heater 2, heat exchanger and deaerator 4 connected in sequence, fixed row expansion vessel 1 is discharged through steam The pipe 6 is connected to the middle of the injection mixing heater 2, the bottom of the injection mixing heater 2 is connected to a water supply pipe for replenishing softened water, and the top of the injection mixing heater 2 is connected to a heat exchanger. Water inlet pipe 8 and steam exhaust pipe 9 are distributed on the top of deaerator 4, and water inlet pipe 8 and steam exhaust pipe 9 are all connected to heat exchanger.

In this embodiment, the fixed-row expansion vessel 1 is a cylindrical shell, the water outlet pipe 7 is at the bottom of the fixed-row expansion vessel 1, the steam discharge pipe 6 is arranged at the top of the fixed-row expansion vessel 1, and the heat exchanger is preferably a surface heat exchanger. Heater3.

This system ejects the exhausted steam in the fixed-discharge expansion vessel 1 through high-pressure supplementary demineralized water, and the demineralized water is heated in the injection mixing heater 2, and the exhausted steam is condensed into water at the same time. The exhaust steam from the deaerator 4 is sent to the surface heat exchanger 3 to further heat the hot water heated in the ejector mixing heater 2, and then the heated hot water enters the deaerator 4, so that the expansion vessel can be arranged The heat and water generated in 1 are all recycled, and the heat and working medium of deaerator 4 are also well recycled.

Because the amount of steam produced by the fixed row expansion vessel 1 is unstable, an electric regulating valve is installed at the outlet of the water pump 5 used for pressurization on the supplementary demineralized water pipeline to regulate and control the supplementary demineralized water volume entering the injector mixing heater 2, Keep the water temperature at the outlet of the ejector mixing heater 2 stable.

In addition, after the fixed-row sewage and various high-temperature hydrophobic water entering the fixed-row expansion vessel 1 are flashed in the fixed-row expansion vessel 1, part of it becomes clean steam, and the remaining water has a higher alkalinity. Higher water is discharged to the flue gas desulfurization system 10, which not only recovers heat and working fluid, but also because this part of water contains high concentration of phosphate and alkalinity, it can prevent internal corrosion of the hot water pipe network, and is more conducive to smoke Gas desulfurization.

The working principle of this system is: the sewage from the boiler is saturated water corresponding to the working pressure of the boiler, with high temperature and high enthalpy value. After entering the fixed row expansion vessel 1 through the 8 inlet pipes, the pressure suddenly drops, and the gasification point of the sewage The original saturated state is destroyed, part of the water releases heat to become saturated water under the new pressure, and part of the water absorbs the latent heat of vaporization to become steam. The steam rises in the fixed row expansion vessel 1, and completes the whole separation process of steam and water after rising for a period of time; the fixed row expansion vessel 1 relies on gravity to separate steam and water, thereby obtaining steam with low salt content. After the fixed-row sewage and various high-temperature hydrophobic water entering the fixed-row expansion vessel 1 are flashed in the fixed-row expansion vessel 1, part of it becomes clean steam, and the remaining water has a higher alkalinity, so the alkalinity of this part can be higher The desulfurized water is discharged to the flue gas desulfurization system 10; the supplementary demineralized water boosted by the water pump 5 enters the injection mixing heater 2, and the flow velocity of the supplementary demineralized water increases instantly after passing through the injection mixing heater 2, and the injection mixing heater Vacuum is formed in 2, at this time, the steam generated by the fixed row expansion vessel 1 is injected into the injection mixed heater 2 under the action of the pressure difference, and directly contacts with the replenishing demineralized water for heat exchange, and the steam condenses into water; in order to further improve At the same time, the heat of the deaerator 4 is recovered at the water temperature, and the condensed water is further introduced into the surface heat exchanger 3 for heating. The heated hot water in the heater 2, and then the hot water at a higher temperature enters the deaerator 4 through the water inlet pipe 8, so that the heat and water generated by the fixed row expansion vessel 1 are recycled, and the heat of the deaerator 4 And the working fluid is also well recycled. This system can not only recover the heat and water generated by the fixed row expansion vessel 1, but also recover the heat and working fluid of the deaerator 4.

Claims (7)

1. A fixed row expansion vessel and deaerator waste steam waste heat recovery system is characterized in that it comprises a fixed row expansion vessel connected in sequence, an injection mixing heater, a heat exchanger and a deaerator, and the injection mixing The heater is connected to the water supply line for replenishing softened water. 2. A fixed row expansion vessel and deaerator waste steam waste heat recovery system according to claim 1, characterized in that the fixed row expansion vessel is connected to an injection mixed heater through a steam discharge pipe. 3. A system for recovering waste steam and waste heat of a fixed-row expansion vessel and a deaerator according to claim 1, wherein the fixed-row expansion vessel is connected to a flue gas desulfurization system. 4. A fixed-arrangement expansion vessel and deaerator exhaust heat recovery system according to claim 1, characterized in that the heat exchanger is a surface heat exchanger. 5. A system for recovering waste steam and waste heat of a fixed-row expansion vessel and a deaerator according to claim 1, wherein a water pump is provided on the water supply pipe. 6. A system for recovering waste steam and waste heat of a fixed row expansion vessel and a deaerator according to claim 4, wherein the outlet of the water pump is provided with an electric regulating valve. 7. A fixed-row expansion vessel and deaerator exhaust heat recovery system according to claim 1, characterized in that the deaerator is connected to a heat exchanger through an exhaust pipe and a water inlet pipe.