CN214936774U

CN214936774U - Desalination system for high-salt-content glycol wastewater

Info

Publication number: CN214936774U
Application number: CN202022694856.7U
Authority: CN
Inventors: 王大新; 张欣然; 施小林; 温春兴
Original assignee: Zhejiang Yidi Environmental Equipment Co ltd
Current assignee: Zhejiang Yidi Environmental Equipment Co ltd
Priority date: 2020-11-19
Filing date: 2020-11-19
Publication date: 2021-11-30
Anticipated expiration: 2030-11-19

Abstract

The utility model particularly relates to a desalination system for high salt content ethylene glycol waste water, including the buffer pool, pass through the multimedium filter that the elevator pump is connected with the buffer pool, the electrodialysis unit be connected with the multimedium filter, set up the desalination liquid water tank in the electrodialysis unit, with the concentrate water tank and the evaporative crystallization unit of electrodialysis unit connection, the evaporative crystallization unit is connected with the concentrate water tank, and desalination liquid water tank upper portion is connected with the passageway, and passageway one end is connected with ethylene glycol tail gas processing apparatus. The utility model discloses use the electrodialysis unit as the whole process system of core, can high-efficiently get rid of the salt that highly contains enrichment in the salt ethylene glycol waste water, entire system long service life, it is comparatively simple and convenient to operate, degree of automatic control is high, and the dense water of output contains the salt content height, and the water yield is few, can reduce the investment cost and the operational load of follow-up evaporation crystallization unit, reduces whole system energy consumption.

Description

Desalination system for high-salt-content glycol wastewater

Technical Field

The utility model belongs to the technical field of the mine water treatment, concretely relates to a desalination system for high salt ethylene glycol waste water that contains.

Background

In 2015, the global ethylene glycol production capacity reaches 3100 kiloton/a, the production is about 2515 kiloton, and the average operation load of the device is 81.13%. For nearly 10 years, China has been the world's largest consumer of ethylene glycol. In 2008, the consumption of ethylene glycol in China accounts for 40% of the total world output, in 2015, the apparent consumption of ethylene glycol in China is 1312 ten thousand t and accounts for about 52% of the total world output, the proportion of the consumption of ethylene glycol in China to the total world output is increased year by year in the period from 2001 to 2016, the annual average annual growth rate of the consumption of ethylene glycol in China is 13.09%, and the highest annual growth rate is 28.75% of 2001. Due to the rapid increase of the demand, the increase of the production capacity of the glycol is promoted, and in recent two years, multiple large-scale glycol production devices are built in China for production. However, the problem of environmental pollution caused by ethylene glycol production is not negligible, and in recent years, with the increasing attention of the world to the fields of environmental protection and wastewater recovery, the treatment of high-salt organic wastewater is more and more concerned. The deep sea gas field development is the direction of future offshore oil development, but in the process of natural gas extraction, the temperature of the pipeline natural gas is reduced along with the increase of the water depth, and natural gas hydrate is easily generated due to the change of temperature and pressure, and is an ice and snow-like compound which is easy to block a shaft, a pipeline and a stratum, thereby seriously influencing the production and transportation operation of the gas field, and in order to avoid the formation of the natural gas hydrate, ethylene glycol is usually adopted as a hydrate inhibitor. Ethylene Glycol (MEG) is widely used as a hydrate inhibitor in anti-hydration agents for gas field mining. Due to the large consumption of the ethylene glycol, the gas field wastewater contains a large amount of ethylene glycol pollutants. Offshore gas field development is specific to land, and formation water often contains a large amount of salt ions due to the specific location of development for offshore gas fields. Therefore, the produced water of the deep sea gas field is typical high-salt organic wastewater, contains high-concentration ethylene glycol and is rich in salt. Due to the particularity of salt in water of the offshore gas field and the limitation of a platform, how to determine the method for treating the high-salt glycol wastewater suitable for the offshore gas field is very important.

At present, the method for treating the high-salt glycol wastewater of the offshore gas field mainly comprises the traditional biochemical method, evaporative crystallization, membrane distillation and MRU glycol recovery desalination system. The biochemical method adopts AO technology, the method firstly dilutes the waste water in a regulating reservoir to 8000-fold salt content 10000mg/l, and nitrate nitrogen is reversely digested and COD is degraded through the anaerobic and aerobic processes. However, the high-salt property of the waste water greatly reduces the biochemical performance, and the waste water needs to be diluted and then subjected to biochemical treatment, so that the operation is complicated. Large occupied area and is not suitable for the treatment and application of large water quantity of offshore platforms. Most importantly, the method cannot recover the glycol in the wastewater, and is waste. The evaporative crystallization technology has two defects, namely, the operation temperature of evaporative crystallization is higher, the loss amount of ethylene glycol is large, the energy consumption is high, and secondly, the crystallization supersaturation degree in the evaporative crystallization process is uncontrollable, the particle size distribution of crystal products is not uniform, the crystal surface defects are more, and the solid-liquid separation in the later period is difficult. The membrane distillation technology is a new technology developed in recent years, materials used for research are generally simple aqueous solutions, and research on industrial wastewater is little. The research work is mostly in the experimental stage, the quantitative analysis on the influence of mass transfer and heat transfer mechanisms and parameters is not enough, the membrane cost is high, the distillation flux is small, and the operation state is unstable due to the influence of temperature polarization and concentration polarization. The MRU glycol recovery desalination system is used as a wide treatment technology for treating high-salt glycol wastewater on an offshore platform, and has some defects. The MRU is a closed cycle and onshore MRU systems are mainly regenerative MRUs, whose main purpose is to evaporate the water to obtain a lean MEG of appropriate concentration. Therefore, all salt ions will accumulate inside the MRU, partly with the barren solution into the downstream process. Due to the fact that the regeneration temperature is high, salt ions can form scales on the surfaces of a reboiler and a heat exchanger after long-term operation, the problems of heat efficiency reduction and serious corrosion are caused, salt concentration cannot be removed in a closed circuit, the concentration is always increased, the salt concentration needs to be accurately controlled, once the salt concentration exceeds the saturated concentration and is separated out, MRU equipment scaling, blockage and serious corrosion can be caused, the system is shut down, and even freezing and blocking of a sea pipe are caused. Therefore, how to efficiently recover the glycol in the wastewater and remove the salt in the wastewater is a key problem in the treatment of the multi-element high-salt organic wastewater.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to overcome exist not enough among the above-mentioned prior art to provide a desalination system for high salt ethylene glycol waste water that contains.

The utility model provides a technical scheme that its technical problem adopted is:

a desalination system for glycol wastewater with high salt content is characterized in that: the device comprises a buffer tank, a multi-media filter connected with the buffer tank through a lift pump, an electrodialysis unit connected with the multi-media filter, a desalted liquid water tank arranged in the electrodialysis unit, a concentrated liquid water tank connected with the electrodialysis unit and an evaporative crystallization unit, wherein the evaporative crystallization unit is connected with the concentrated liquid water tank.

Furthermore, the upper part of the desalting liquid water tank is connected with a channel, and one end of the channel is connected with a glycol tail gas treatment device.

Furthermore, the desalting solution tank is provided with an overflow pipe, and one end of the overflow pipe is connected with a water producing tank.

Further, be provided with the concentrate pond between concentrate water tank and the evaporative crystallization unit, the concentrate pond passes through the overflow pipe with the concentrate water tank and is connected, and the concentrate pond passes through the efflux pump with the evaporative crystallization unit and is connected.

Compared with the prior art, the utility model, have following advantage and effect:

(1) the method can remove the salt enriched in the glycol wastewater with high salt content, and solves the problems of greatly reduced effect and high risk of the traditional treatment method caused by salt enrichment in the recycling process of the glycol wastewater with high salt content;

(2) the desalination system adopts an electrodialysis unit process, the whole process has low requirement on the quality of inlet water, the electrodialysis ion exchange membrane has long service life, and organic ethylene glycol cannot be intercepted on one side of saline water by an ion exchange membrane all the time in the desalination process, so that the recovery rate of the ethylene glycol is greatly improved, the salt content of concentrated water is high, the produced concentrated water is low in quantity, the investment cost and the operation load of a subsequent evaporation crystallization unit can be reduced, and the operation energy consumption of the whole system is greatly reduced;

(3) compared with the traditional treatment method, the whole process system taking the electrodialysis unit as the core is simple and convenient to operate, high in automatic control degree and suitable for the waste water treatment area with limited floor area, such as an offshore platform.

Drawings

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

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application.

Detailed Description

In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.

Examples are given.

As shown in fig. 1, the present embodiment includes a buffer tank 1, a multimedia filter 2 connected to the buffer tank 1, an electrodialysis unit 3 connected to the multimedia filter 2, a desalted liquid tank 4, a concentrated liquid tank 5, and an evaporative crystallization unit 9. The buffer tank 1 is used for accumulating waste water and can regulate the discharge of the waste water. The multi-media filter 2 is connected with the buffer tank 1 through the lift pump 91, and the multi-media filter 2 is used for removing large particulate matters and organic matters such as suspended matters, colloids and the like in the wastewater so as to ensure that the turbidity of the wastewater entering the electrodialysis unit 3 is less than 1 NTU. The electrodialysis unit 3 is connected with the multi-medium filter 2 through a pipeline, the desalted liquid water tank 4 is arranged in the electrodialysis unit 3 and is connected with the electrodialysis unit 3, and the concentrated liquid water tank 5 is connected with the electrodialysis unit 3. The concentrated solution water tank 5 is internally provided with concentrated solution required by the electrodialysis process, specifically, after the waste water which is filtered by the multi-media filter 2 and reaches the standard enters the electrodialysis unit 3, after the electrodialysis unit 3 works, salt ions in the waste water move in the electrodialysis unit 3, including the migration of cations to negative electrodes, the migration of anions to positive electrodes through cation exchange membranes, and the migration of ions in the salt water to the concentrated solution through anion exchange membranes, so that the salt water in the desalted solution water tank 4 is desalted, and meanwhile, the concentrated solution is further concentrated.

The desalted liquid water tank 4 is provided with an overflow pipe 92, one end of the overflow pipe 92 is connected with the water producing tank 6, specifically, when the salt content of the brine in the desalted liquid water tank 4 reaches a set value, the brine is gradually accumulated until overflowing from the overflow pipe 92 into the water producing tank 6, and the water producing tank 6 is used for accumulating the desalted water liquid (mainly glycol solution) and outputting the water liquid to other devices for recycling.

The upper part of the desalting solution water tank 4 is connected with a channel, one end of the channel is connected with a glycol tail gas treatment device 7, and the glycol tail gas treatment device 7 is used for sucking out and treating part of volatilized glycol to prevent toxic glycol from being discharged into the atmosphere.

The concentrated solution tank 5 is provided with an overflow pipe 92, one end of the overflow pipe 92 is connected with the concentrated solution tank 8, and specifically, when the salt content of the concentrated solution in the concentrated solution tank 5 reaches a set target value, the salt content is gradually accumulated until the salt content overflows from the overflow pipe 92 into the concentrated solution tank 8. The concentrated solution pool 8 is connected with an evaporative crystallization unit 9 through an external discharge pump, and the evaporative crystallization unit 9 is used for preparing the concentrated solution into solid salt particles through evaporative crystallization.

The desalination system for high salt content glycol waste water that this embodiment describes can remove the salt that the high salt content glycol waste water is enriched, has solved the traditional processing method effect greatly reduced that high salt content glycol waste water cyclic recycle in-process salt enrichment caused, and the problem that danger is high. This desalination system adopts electrodialysis unit 3 technology, and whole process requires the stalk low to the quality of water of intaking, and electrodialysis ion exchange diaphragm long service life, and organic matter ethylene glycol is not permeable ion exchange membrane all the time and is detained on one side of salt water at the in-process of desalination to the rate of recovery of ethylene glycol has been improved greatly, and concentrated dense water contains the salt content height, and the dense water volume of output is few, can reduce the investment cost and the operation load of follow-up evaporation crystallization unit 9, makes the low greatly reduced of whole system operation energy consumption. Compared with the traditional treatment method, the whole process system taking the electrodialysis unit 3 as the core is simple and convenient to operate, has high automatic control degree, and is very suitable for a wastewater treatment area with limited floor area, such as an offshore platform.

The above description in this specification is merely illustrative of the present invention. Various modifications, additions and substitutions may be made by those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.

Claims

1. A desalination system for glycol wastewater with high salt content is characterized in that: the device comprises a buffer tank, a multi-media filter connected with the buffer tank through a lift pump, an electrodialysis unit connected with the multi-media filter, a desalted liquid water tank arranged in the electrodialysis unit, a concentrated liquid water tank connected with the electrodialysis unit and an evaporative crystallization unit, wherein the evaporative crystallization unit is connected with the concentrated liquid water tank;

the upper part of the desalting liquid water tank is connected with a channel, and one end of the channel is connected with a glycol tail gas treatment device; the desalting liquid water tank is provided with an overflow pipe, and one end of the overflow pipe is connected with a water producing tank;

and a concentrated solution tank is arranged between the concentrated solution water tank and the evaporative crystallization unit, the concentrated solution tank is connected with the concentrated solution water tank through an overflow pipe, and the concentrated solution tank is connected with the evaporative crystallization unit through an external discharge pump.