阅读说明：本技术 一种低品位热源耦合多效闪蒸浓缩蒸发系统 (Low-grade heat source coupling multi-effect flash evaporation concentration evaporation system ) 是由 赵亮 张娟 王次成 张国付 刘平元 陶晔 于 2020-04-24 设计创作，主要内容包括：本发明公开了一种低品位热源耦合多效闪蒸浓缩蒸发系统,属于废水处理技术领域。包括热源系统、多效蒸发浓缩系统及两者之间的连接热源管组成。通过热源系统将电厂的低品位热源梯级闪蒸成低温蒸汽,分别进入多效蒸发浓缩系统的效体加热器,作为多效蒸发浓缩系统的蒸发热源,实现热源系统与多效蒸发浓缩系统的灵活耦合。实现低品位热水热源的高效利用,降低了多效蒸发浓缩系统的运行能耗。(The invention discloses a low-grade heat source coupling multi-effect flash evaporation concentration evaporation system, and belongs to the technical field of wastewater treatment. Comprises a heat source system, a multi-effect evaporation and concentration system and a connecting heat source pipe between the heat source system and the multi-effect evaporation and concentration system. The low-grade heat source of the power plant is flash evaporated into low-temperature steam in a gradient manner through the heat source system, and the low-temperature steam enters the effect body heaters of the multi-effect evaporation concentration system respectively to serve as evaporation heat sources of the multi-effect evaporation concentration system, so that the flexible coupling of the heat source system and the multi-effect evaporation concentration system is realized. The high-efficiency utilization of the low-grade hot water heat source is realized, and the operation energy consumption of the multi-effect evaporation concentration system is reduced.)

1. A low-grade heat source coupling multi-effect flash evaporation concentration evaporation system is characterized by comprising a heat source system and a multi-effect evaporation concentration system; the heat source system comprises a multi-stage heat source unit, a heat source flash tank and a spraying layer are arranged in the heat source unit, and hot water sequentially enters the heat source flash tank of the multi-stage heat source unit and is flashed out steam through the spraying layer to form multi-stage steam; the multi-effect evaporation concentration system comprises a multi-effect evaporation concentration unit, wherein an effective body heater, an effective body separator and an effective body circulating pump are arranged in the evaporation concentration unit, and the effective body heater is in circulating connection with a wastewater outlet of the effective body separator through the effective body circulating pump;

the multi-stage steam generated by the multi-stage heat source unit is connected with an effect body heater of the multi-effect evaporation concentration unit; the steam outlet of the effective body separator of the low-efficiency evaporation concentration unit is connected with the effective body heater of the next-effect evaporation concentration unit, so that the evaporation concentration units are connected in series; the effect body heater of the first effect evaporation concentration unit is connected with starting steam, the effect body separator is connected with wastewater feeding, the steam outlet of the effect body separator of the last effect evaporation concentration unit is connected with a discharge pump through a condenser and a vacuum pump, and the wastewater outlet of the effect body separator is connected with the discharge pump.

2. The low-grade heat source coupling multi-effect flash evaporation concentration evaporation system as claimed in claim 1, wherein the energy of the heat source system is from flue gas at the tail of a boiler, a hot water heat exchanger is arranged in the flue, and hot water generated by the hot water heat exchanger sequentially enters a multi-stage heat source unit and flows back to the hot water heat exchanger through a hot water reflux pump.

3. The low-grade heat source coupling multi-effect flash evaporation, concentration and evaporation system as claimed in claim 2, wherein the hot water heat exchanger is a low-temperature economizer before or after dust removal.

4. The low-grade heat source coupled multi-effect flash evaporation, concentration and evaporation system of claim 1, wherein the number of stages of the multi-stage heat source unit is greater than or equal to 1, and the number of stages of the multi-effect flash evaporation and concentration unit is greater than or equal to 1.

5. The low-grade heat source coupling multi-effect flash evaporation concentration evaporation system as claimed in claim 1, wherein the multi-stage steam generated by the multi-stage heat source unit is connected with the effect body heater of the multi-effect flash evaporation concentration unit through a heat source pipe, and the heat source pipe is provided with a regulating valve and a check valve.

Technical Field

The invention relates to a low-grade heat source coupling multi-effect flash evaporation concentration evaporation system, and belongs to the technical field of wastewater treatment of thermal power plants.

Background

The vast majority of coal-fired power plants in China adopt a limestone-gypsum wet desulphurization process. In order to maintain the safe and stable operation of the wet desulphurization system, a certain amount of desulphurization wastewater must be discharged. The desulfurization wastewater has very poor water quality, contains a large amount of sulfate radicals, chloride ions, calcium and magnesium ions, heavy metals and the like, and can cause serious pollution to the environment. Many of the heavy metal ions are the first pollutants required to be controlled in the national environmental protection standard, so the desulfurization wastewater generated in the traditional process must be separately treated.

At present, the conventional desulfurization wastewater treatment system adopts a 'triple-box' chemical precipitation method, has complex process system, more equipment, poor working environment and high investment and operating cost, and can not remove the salt such as chloride ions in wastewater, thereby being incapable of recycling. From the long-term development point of view, the three-header process does not meet the environmental protection requirement. And with the stricter requirements of the country on water resource management and wastewater discharge and the policy of limiting discharge of high-salinity wastewater issued by part of local governments, the coal-fired power plant can meet the requirement of environmental protection only by carrying out the work of zero discharge of wastewater. At present, the total salt content, chloride ions, hardness, suspended matters and heavy metal content of the wet desulphurization wastewater are very high, the recycling approach is very limited, and the treatment difficulty is very large. At present, the treatment process of pretreatment (chemical softening + separation) + concentration (membrane concentration/thermal concentration) + solidification (evaporative crystallization/flue evaporation) "is generally adopted, and the investment and operation cost are very high.

Thermal concentration is a good wastewater reduction process, and a multi-effect flash evaporator or a mechanical compression recirculation evaporator is mainly used. Wherein the multi-effect flash evaporator uses steam as a heat source to evaporate and concentrate the wastewater, and the steam parameter is saturated steam with the temperature of about 100 ℃. The power plant generally has no saturated steam suitable for the operation of the multi-effect flash evaporator, and the saturated steam is required to be used as a heat source of the multi-effect flash after being subjected to temperature and pressure reduction through a temperature and pressure reducer, so that the high-grade energy is low in use, and the operation cost is high. Because the hardness of the desulfurization wastewater is high, the direct use of high-temperature steam can cause scaling of a heat exchange surface, and the safe and stable operation of the multi-effect flash evaporator is influenced. Although a heat source suitable for multi-effect flash evaporation and concentration is not easy to obtain in a power plant, a large number of low-grade hot water heat sources exist, such as hot water of a tail flue heat exchanger, heat supply circulating water and the like. The waste water is directly heated by hot water, so that the heat exchange area is large, and the scaling risk is increased. Therefore, a process system capable of coupling a low-grade heat source of a power plant to realize multi-effect flash evaporation, evaporation and concentration of wastewater is developed, and the operation cost of desulfurization wastewater treatment can be reduced.

Disclosure of Invention

The invention aims to solve the technical problem of high operating cost of multi-effect flash evaporation.

In order to solve the technical problems, the technical scheme of the invention is to provide a low-grade heat source coupled multi-effect flash evaporation concentration evaporation system, which is characterized by comprising a heat source system and a multi-effect flash evaporation concentration system; the heat source system comprises a multi-stage heat source unit, a heat source flash tank and a spraying layer are arranged in the heat source unit, and hot water sequentially enters the heat source flash tank of the multi-stage heat source unit and is flashed out steam through the spraying layer to form multi-stage steam; the multi-effect evaporation concentration system comprises a multi-effect evaporation concentration unit, wherein an effective body heater, an effective body separator and an effective body circulating pump are arranged in the evaporation concentration unit, and the effective body heater is in circulating connection with a wastewater outlet of the effective body separator through the effective body circulating pump;

the multi-stage steam generated by the multi-stage heat source unit is connected with an effect body heater of the multi-effect evaporation concentration unit; the steam outlet of the effective body separator of the low-efficiency evaporation concentration unit is connected with the effective body heater of the next-effect evaporation concentration unit, so that the evaporation concentration units are connected in series; the effect body heater of the first effect evaporation concentration unit is connected with starting steam, the effect body separator is connected with wastewater feeding, the steam outlet of the effect body separator of the last effect evaporation concentration unit is connected with a discharge pump through a condenser and a vacuum pump, and the wastewater outlet is connected with the discharge pump.

Preferably, the energy of the heat source system comes from flue gas at the tail part of the boiler, a hot water heat exchanger is arranged in the flue, and hot water generated by the hot water heat exchanger sequentially enters the multi-stage heat source unit and flows back to the hot water heat exchanger through a hot water reflux pump.

Preferably, the hot water heat exchanger is a low-temperature economizer before or after dust removal.

Preferably, the number of stages of the multi-stage heat source unit is more than or equal to 1, and the number of stages of the multi-effect evaporation and concentration unit is more than or equal to 1.

Preferably, the multi-stage steam generated by the multi-stage heat source unit is connected with the effect body heater of the multi-effect evaporation concentration unit through a heat source pipe, and the heat source pipe is provided with a regulating valve and a check valve.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides a heat source for a multi-effect evaporation concentration system by coupling a hot water heat source, reduces the operation cost and avoids the heat source grade loss of a high-quality steam heat source.

Drawings

FIG. 1 is a schematic diagram of a low-grade heat source coupled multi-effect flash evaporation concentration evaporation system according to the present invention;

description of reference numerals: 1. the system comprises a heat source system, a multiple-effect evaporation and concentration system, a flue, a low-temperature economizer, a heat source flash tank, a hot water reflux pump, a hot water circulating pump, a spray layer, a heat source pipe, a 17-1 regulating valve I, a 17-2 regulating valve II, a 17-3 regulating valve III, a 18-1 check valve I, a 18-2 check valve II, a 18-3 check valve III, a feeding pump, a 22-effect body heater, a 23-effect body circulating pump, a 24-effect body separator, a 25 vacuum pump, a 26 condenser, a 27 discharging pump, a waste water feeding, B non-condensable gas, C cooling water feeding, D cooling water discharging, E condensed water, F waste water discharging, G circulating water feeding, H circulating water discharging and J starting steam.

Detailed Description

In order to make the invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.