阅读说明：本技术 一种用于电厂高浓度脱硫废水浓缩液深度处理的膜蒸馏工艺 (Membrane distillation process for advanced treatment of high-concentration desulfurization wastewater concentrated solution of power plant ) 是由 王开江 于 2019-03-14 设计创作，主要内容包括：本发明公开了一种用于电厂高浓度脱硫废水浓缩液深度处理的膜蒸馏工艺,废水箱中加入待处理废水通过盐水泵输送到换热器中进行循环加热,待膜蒸馏组件的进料温度达到预设温度时,开启冷却水循环泵和冷却水系统,膜蒸馏组件蒸馏过程开始,产生浓盐水和淡水,浓盐水返回废水箱,淡水经冷却进入到淡水收集瓶。通过调控膜蒸馏系统中进料温度、进料流量、进料电导率、冷却水循环流量工艺参数,显著提高了浓缩液的处理效率,减少了污染物质的排放,提高了废水排放标准。(The invention discloses a membrane distillation process for advanced treatment of a high-concentration desulfurization wastewater concentrated solution in a power plant. By regulating and controlling the technological parameters of the feeding temperature, the feeding flow, the feeding conductivity and the cooling water circulation flow in the membrane distillation system, the treatment efficiency of the concentrated solution is obviously improved, the discharge of pollutants is reduced, and the wastewater discharge standard is improved.)

1. A membrane distillation process for advanced treatment of high-concentration desulfurization wastewater concentrated solution in a power plant is characterized by comprising the following steps:

s1, connecting a membrane distillation system, and adding a high-concentration desulfurization wastewater concentrated solution to be treated into a wastewater tank;

s2, setting the distillation process feeding temperature set value of the membrane distillation assembly to be 67-80 ℃, starting a brine pump, and conveying the high-concentration desulfurization wastewater concentrated solution to a heat exchanger through the brine pump for circulating heating;

s3, controlling the feed flow rate of the membrane distillation assembly to be 2-6m through a flow meter³Controlling the feed conductivity of the membrane distillation assembly to be 106.3-159.7ms/cm by a conductivity meter, starting a cooling water circulating pump and a cooling water system when the feed temperature of the membrane distillation assembly reaches over 67 ℃, and controlling the circulating flow of the cooling water to be 2-6m³The membrane distillation component begins to distill to generate strong brine and fresh water, the strong brine returns to the waste water tank, and the fresh water enters the fresh water collecting bottle after being cooled;

and S4, changing the technological parameters of the feeding temperature, the feeding flow rate, the feeding conductivity and the cooling water circulation flow rate in the membrane distillation system, and repeating the steps.

2. The membrane distillation process for the advanced treatment of high concentration desulfurization wastewater concentrate of a power plant as claimed in claim 1, characterized in that the feeding temperature, the feeding flow rate, the feeding conductivity and the cooling water circulation flow rate are all gradually changed in a slowly increasing manner.

3. The membrane distillation process for the advanced treatment of high concentration desulfurization wastewater concentrate of power plant as claimed in claim 2, characterized in that the membrane distillation system adopts a continuous operation mode, and the operation time is 10-22 days.

4. The membrane distillation process for the advanced treatment of high concentration desulfurization wastewater concentrates of power plants according to claim 1, characterized in that the membrane distillation modules are four membrane distillation modules in series, two membrane distillation modules in parallel in series or four membrane distillation modules in parallel.

5. The membrane distillation process for the advanced treatment of high-concentration desulfurization wastewater concentrate of a power plant according to claim 4, characterized in that the membrane distillation assembly comprises two membrane distillation assemblies connected in series and connected in parallel.

6. The membrane distillation process for the advanced treatment of high concentration desulfurization wastewater concentrates of power plants according to claim 1, characterized in that the membrane distillation method in the membrane distillation system comprises direct contact membrane distillation, reduced pressure or vacuum membrane distillation, air gap membrane distillation, purge gas membrane distillation.

Technical Field

The invention relates to the technical field of high-concentration liquid waste treatment control and environment-friendly purification treatment, in particular to a membrane distillation process for advanced treatment of high-concentration desulfurization wastewater concentrated solution in a power plant.

Background

As of 2009, the installed capacity of electric power in China is as high as 8.52 × 10⁸Kw, wherein the specific gravity of the coal-fired power generation is 74.6%. With the continuous expansion of social and economic scales, coal-fired power generation still occupies a leading position in the energy structure of China. The flue gas treatment method mainly adopts a limestone-gypsum wet flue gas desulfurization method, and the desulfurization waste water produced by the method has very complex water quality, is typical of high salt content, high hardness, high chloride ion concentration, strong corrosivity and scalingHigh pollution of waste water. The waste water not only causes environmental pollution and resource waste, but also influences the development of social economy. Therefore, the zero-emission advanced treatment of the high-concentration desulfurization wastewater concentrate in the power plant becomes a hot spot of current research.

A large amount of high-concentration desulfurization wastewater concentrated solution generated in the desulfurization wastewater treatment process of a power plant has the characteristics of high salt content, high hardness, high total solid content, high corrosivity, concentration polarization and the like, membrane components such as reverse osmosis are utilized for reutilization, the treatment effect is poor, and the membrane components are easily and quickly polluted. In the actual treatment process, a part of high-concentration concentrated solution is subjected to precipitation treatment in a physicochemical treatment mode, so that not only is a large amount of medicament waste and secondary pollution generated, but also certain resource waste is caused; and a part of high-concentration concentrated solution is treated in a high-temperature evaporation crystallization mode, so that the energy consumption is high and the economical efficiency is poor.

Therefore, aiming at the research of the zero-emission advanced treatment problem of the high-concentration desulfurization wastewater concentrated solution, the invention adopts the membrane distillation treatment process, utilizes the advantages of high interception rate, small equipment volume, low energy consumption, high separation efficiency and the like of the membrane distillation technology, researches the removal efficiency of different influencing factors on the desulfurization wastewater concentrated solution under pilot scale conditions, and regulates and controls the process parameters to be in the optimal state. At present, the research on the membrane distillation technology in the process of the zero-emission advanced treatment of the high-concentration desulfurization wastewater concentrated solution in a power plant is less, and particularly, the research is related to the research performed under the pilot-scale test condition.

Disclosure of Invention

In order to solve the problems in the background art, the invention aims to provide a membrane distillation process for advanced treatment of a high-concentration desulfurization wastewater concentrated solution in a power plant, which achieves zero emission standard after advanced treatment of the high-concentration desulfurization wastewater concentrated solution through a series of research and regulation settings of process parameters.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a membrane distillation process for advanced treatment of high-concentration desulfurization wastewater concentrated solution in a power plant, which comprises the following steps:

s1, connecting a membrane distillation system, and adding a high-concentration desulfurization wastewater concentrated solution to be treated into a wastewater tank;

s2, setting the distillation process feeding temperature set value of the membrane distillation assembly to be 67-80 ℃, starting a brine pump, and conveying the high-concentration desulfurization wastewater concentrated solution to a heat exchanger through the brine pump for circulating heating;

s3, controlling the feed flow rate of the membrane distillation assembly to be 2-6m through a flow meter³Controlling the feed conductivity of the membrane distillation assembly to be 106.3-159.7ms/cm by a conductivity meter, starting a cooling water circulating pump and a cooling water system when the feed temperature of the membrane distillation assembly reaches over 67 ℃, and controlling the circulating flow of the cooling water to be 2-6m³The membrane distillation component begins to distill to generate strong brine and fresh water, the strong brine returns to the waste water tank, and the fresh water enters the fresh water collecting bottle after being cooled;

and S4, changing the technological parameters of the feeding temperature, the feeding flow rate, the feeding conductivity and the cooling water circulation flow rate in the membrane distillation system, and repeating the steps.

Furthermore, the feeding temperature, the feeding flow rate, the feeding conductivity and the cooling water circulation flow rate are gradually changed in a slowly increasing mode.

Further, the membrane distillation system adopts a continuous operation mode, and the operation time is 10-22 days.

Further, the membrane distillation assemblies are four membrane distillation assemblies connected in series, two membrane distillation assemblies connected in series and two membrane distillation assemblies connected in parallel or four membrane distillation assemblies connected in parallel. The membrane distillation modules are preferably two membrane distillation modules connected in series and in parallel.

Further, the membrane distillation method in the membrane distillation system includes direct contact membrane distillation, reduced pressure or vacuum membrane distillation, air gap membrane distillation, and purge gas membrane distillation.

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

the method has the advantages of simple process, easy control, improved recovery rate of the desulfurization wastewater concentrated solution, reduced actual energy consumption and no secondary pollution. The membrane distillation technology is applied to the zero-emission advanced treatment process of the high-concentration desulfurization wastewater concentrated solution, so that the pollution tolerance capacity of the membrane is improved, membrane pollution to a certain degree is reduced, the service life of a membrane component is prolonged, and the stability and the economy of operation are improved; and the membrane distillation technology does not need membrane pressure difference required by membrane components such as reverse osmosis and the like, so that energy loss in the actual process is reduced, meanwhile, the membrane distillation technology can utilize low-quality heat sources generated by a power plant, and substances are transmitted at a temperature lower than the boiling point of waste liquid, so that resource utilization can be maximized, and the membrane distillation technology is environment-friendly and energy-saving.

The membrane distillation system is used as a desulfurization wastewater zero-discharge treatment process, so that the treatment efficiency of the concentrated solution is improved, the discharge of pollutants is reduced, and the wastewater discharge standard is improved. The experiment result shows that the interception rate is up to 100 percent, the total dissolved solids of the produced water is 3.9-6.5mg/L, and the conductivity of the produced water is 8.6-9.9 us/cm.

Drawings

The invention is described in further detail below with reference to specific embodiments and with reference to the following drawings.

FIG. 1 is a block diagram of a membrane distillation system according to the present invention;

FIG. 2 is a graph of the effect of feed temperature on membrane flux;

FIG. 3 is a graph of the effect of feed flow on membrane flux;

FIG. 4 is a graph of the effect of cooling water circulation flow on membrane flux;

FIG. 5 is a graph of the effect of increasing feed flow and cooling water circulation flow in proportion on membrane flux;

FIG. 6 is a graph of the effect of feed conductivity on membrane flux;

FIG. 7 is an electron micrograph of the initial surface contamination of the film;

FIG. 8 is an electron micrograph of the contamination of the film surface after 1 month of operation;

FIG. 9 is an electron micrograph of the contamination of the film surface after 2 months of operation;

wherein, waste water tank 1, salt water pump 2, heat exchanger 3, flowmeter 4, cooling water circulating pump 5, cooling water system 6, membrane distillation subassembly 7.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the following detailed description is made with reference to the accompanying drawings and the detailed description.

The structure of the membrane distillation system is shown in figure 1, a high-concentration desulfurization wastewater concentrated solution in a wastewater tank 1 on the left side enters a heat exchanger 3 through a brine pump 2 to be circularly heated, and a flow meter 4, a conductivity meter, a thermometer and a pressure gauge are respectively installed on a pipeline between the heat exchanger and a membrane distillation assembly and used for measuring the flow, the conductivity, the temperature and the pressure of wastewater before entering a membrane distillation assembly 7. And starting a cooling water circulating pump 5 and a cooling water system 6, installing a flow meter 4 on a pipeline between the cooling system and the membrane distillation assembly for measuring the circulating flow of the cooling water, starting the distillation process of the membrane distillation assembly 7 to generate strong brine and fresh water, returning the strong brine to the waste water tank 1, and cooling the fresh water to enter the fresh water collecting bottle.

The membrane distillation process for the advanced treatment of the high-concentration desulfurization wastewater concentrated solution in the power plant comprises the following steps:

s1, connecting a membrane distillation system, and adding a high-concentration desulfurization wastewater concentrated solution to be treated into the wastewater tank, wherein the properties of the high-concentration desulfurization wastewater concentrated solution are shown in Table 1;

TABLE 1

Index (I)	Numerical value
		Total hardness mg/L	28.5-32
Ca2+mg/L	10.0-11.0
		Mg2+mg/L	2.0-2.19
Conductivity ms/cm	106.3-159.7
		Total chemical oxygen demand mg/L	720-765
Cl-mg/L	20000-25200

S2, setting the distillation process feeding temperature set value of the membrane distillation assembly to be 67-80 ℃, starting a brine pump, and conveying the high-concentration desulfurization wastewater concentrated solution to a heat exchanger through the brine pump for circulating heating;

s3, controlling the feed flow rate of the membrane distillation assembly to be 2-6m through a flow meter³Controlling the feed conductivity of the membrane distillation assembly to be 106.3-159.7ms/cm by a conductivity meter, starting a cooling water circulating pump and a cooling water system when the feed temperature of the membrane distillation assembly reaches over 67 ℃, and controlling the circulating flow of the cooling water to be 2-6m³The membrane distillation component begins to distill to generate strong brine and fresh water, the strong brine returns to the waste water tank, and the fresh water enters the fresh water collecting bottle after being cooled;

and S4, changing the technological parameters of the feeding temperature, the feeding flow rate, the feeding conductivity and the cooling water circulation flow rate in the membrane distillation system, and repeating the steps.

Wherein, the feeding temperature, the feeding flow, the feeding conductivity and the cooling water circulation flow are gradually changed in a slowly increasing mode. The membrane distillation system adopts a continuous operation mode, and the operation time is 10-22 days.

Wherein, the membrane distillation assembly is four membrane distillation assemblies connected in series, two membrane distillation assemblies connected in parallel in series or four membrane distillation assemblies connected in parallel. The membrane distillation modules are preferably two membrane distillation modules connected in series and in parallel.

The membrane distillation method in the membrane distillation system comprises direct contact type membrane distillation, reduced pressure or vacuum membrane distillation, air gap type membrane distillation and purge gas membrane distillation.

In the test process, the total hardness, calcium ion concentration and magnesium ion concentration in the wastewater are measured by an EDTA titration method (GB/T7477-1987); the conductivity is measured by a conductivity meter method in Water and wastewater monitoring and analyzing methods in China; measuring the chloride ion concentration by inorganic anion chromatography (HJ 84-2016); the chemical oxygen demand was measured by dichromate method (HJ828-2017), and is shown in Table 2.

TABLE 2

Item	Measurement method
		Total hardness, calcium, magnesium ion concentration	EDTA titration method (GB/T7477-1987)
Electrical conductivity of	Conductivity meter method
		Concentration of chloride ion	Ion chromatography (HJ 84-2016)
Chemical Oxygen Demand (COD)	Dichromate method (HJ828-2017)