CN107459191B

CN107459191B - Efficient oil field sewage treatment system

Info

Publication number: CN107459191B
Application number: CN201610388068.0A
Authority: CN
Inventors: 林日亿; 韩超杰; 贾志英; 翟翀; 王新伟; 杨德伟
Original assignee: China University of Petroleum East China
Current assignee: China University of Petroleum East China
Priority date: 2016-06-02
Filing date: 2016-06-02
Publication date: 2022-03-11
Anticipated expiration: 2036-06-02
Also published as: CN107459191A

Abstract

The invention provides a novel and efficient oil field sewage treatment system combining a pretreatment system and an advanced treatment system, which mainly comprises a gravity separator, a liquid storage tank, a water feeding pump, a heat exchanger I, a heat exchanger II, a heat exchanger III, a mixer, a delivery pump, an evaporator, a compressor, a boiler and an oil extraction system. The pretreatment system carries out primary treatment on the oil field sewage, and the gravity separator is utilized to filter the oil field sewage out of the pretreated sewage. The pretreated sewage is respectively heated by high-temperature high-pressure steam and steam condensate, the concentrated solution generated after heated evaporation returns to the separation tank for continuous separation, and the condensate after heat exchange enters the boiler as boiler water supplement. Through the combination of the sewage pretreatment process and the advanced treatment process, the high-temperature produced liquid waste heat is utilized, the efficient treatment process of the oil field sewage is realized, the advanced treatment system realizes the internal heat exchange of the system, the external energy consumption is saved, and the economical efficiency is improved.

Description

Efficient oil field sewage treatment system

Technical Field

The invention relates to a sewage treatment system for an oil field in the petroleum industry, in particular to a sewage pretreatment and advanced treatment system which are combined to form an effective circulation.

Background

Petroleum is an important strategic resource and has important effects on national economic development and improvement of the living standard of people. In the process of petroleum exploitation for a long time, the produced industrial sewage is discharged only after simple precipitation and oil-water separation, which causes great damage to the ecological environment and waste of resources.

At present, most oil fields in China enter the middle and later stages of oil development, the water content in produced liquid is 70% -80%, some of the produced liquid even reaches more than 90%, the daily oil-containing sewage quantity is very large, and more than 5t of oil field sewage can be generated when 1t of crude oil is produced. The national crude oil yield in 2013 is calculated to be 2.0 hundred million t, the annual water injection amount is up to 12 hundred million t, and the annual water injection amount is increased by more than 2 percent, so that the water consumption of the oil field water injection system engineering is large. The temperature of the produced liquid of the steam huff and puff and steam flooding oil well reaches 80 ℃, the temperature of the produced liquid of the SAGD well reaches more than 140 ℃, the SAGD well is rich in a large amount of medium and high quality waste heat resources, if the high-temperature sewage separated by the combined station is directly discharged without being treated, the pollution of soil and water sources can be caused, even the burning accident of dirty oil can be caused, the life and property safety is seriously threatened, and meanwhile, because the temperature of the sewage is higher, a large amount of heat can be wasted by directly discharging, and the heat pollution is generated.

Therefore, the direct discharge of a large amount of oil field sewage can not only cause the problems of environmental and ecological pollution, but also contradict the policy of energy conservation and emission reduction. On the contrary, if the oil field sewage is effectively treated and reinjected, the method not only can meet the increasing requirement of water injection amount in the oil field exploitation process, but also can save water resources, reduce environmental pollution, recover waste heat and bring economic benefits to the oil field, and is favorable for the green sustainable development of the oil field. Therefore, the invention provides a novel idea for treating the oil field sewage.

Disclosure of Invention

Aiming at the defects of the traditional oil field sewage treatment method, the invention provides a novel and efficient oil field sewage treatment system combining pretreatment and advanced treatment.

The sewage treatment system comprises a sewage pretreatment system and an advanced treatment system; the pretreatment system comprises a gravity separator, a liquid storage tank, a water feed pump and a heat exchanger; the advanced treatment system comprises a heat exchanger, a mixer, a delivery pump, an evaporator and a compressor. The pretreatment system carries out primary treatment on the oil field sewage, and the gravity separator is utilized to filter the oil field sewage out of the pretreated sewage. The pretreated sewage is respectively heated by high-temperature high-pressure steam and steam condensate, the concentrated solution generated after heated evaporation returns to the separation tank for continuous separation, and the condensate after heat exchange enters the boiler as boiler water supplement.

The pretreatment system carries out preliminary treatment to oil field sewage, utilizes gravity separator (1) to divide into the water and the silt of lower floor and the oil on upper strata with oil field sewage, and oil is collected from the left side, and silt is discharged from the lower floor, and water gets into liquid storage pot (2) from the right side for subsequent use.

Before the sewage enters the advanced treatment system, the sewage is preheated by a heat exchanger (4), and a heating medium is high-temperature produced liquid produced from an oil well.

The sewage enters the tube side of an evaporator (9) after being preheated by a heat exchanger II (5) and a heat exchanger III (6) in an advanced treatment system and is heated by high-temperature high-pressure steam on the shell side, the residual concentrated solution after the water vapor is evaporated from the sewage on the tube side by heating enters the heat exchanger II (5) to heat the sewage after pretreatment, the condensed water condensed from the water vapor on the shell side enters the heat exchanger III (6) to heat the sewage after pretreatment, and the condensed water after heat exchange enters a boiler as boiler water supplement.

Through the combination of the sewage pretreatment process and the advanced treatment process, the high-efficiency treatment process of the oil field sewage is realized by utilizing the waste heat of the high-temperature produced liquid, and the advanced treatment system realizes the internal heat exchange of the system, so that compared with the conventional oil field sewage treatment system, the system saves the external energy consumption and improves the economical efficiency.

Drawings

FIG. 1 is a schematic diagram of a novel oilfield wastewater treatment system; the names of the components are as follows:

1-gravity separator, 2-liquid storage tank, 3-water feeding pump, 4-heat exchanger, 5-heat exchanger, 6-heat exchanger, 7-mixer, 8-delivery pump, 9-evaporator, 10-compressor, 11-boiler, 12-oil extraction system, pretreatment system-001 and deep treatment system-002.

Wherein the pretreatment system 001 consists of a gravity separator (1), a liquid storage tank (2), a water feeding pump (3) and a heat exchanger (4); the advanced treatment system 002 comprises a heat exchanger (5), a heat exchanger (6), a mixer (7), a delivery pump (8), an evaporator (9) and a compressor (10).

Detailed Description

A novel high-efficiency sewage treatment system comprises a pretreatment system and an advanced treatment system. The invention is described in detail below with reference to the attached drawing figures:

the specific process flow is as follows: the sewage separated from the gravity separator (1) enters the liquid storage tank (2), the sewage in the liquid storage tank (2) enters the heat exchanger (4) through the water feeding pump (3), and the sewage is preheated by the high-temperature produced liquid in the heat exchanger (4), wherein the above process is a pretreatment process. The advanced treatment system is divided into two paths for the preheated sewage: one path enters a heat exchanger II (5), sewage is heated again in the heat exchanger II (5), and a heating medium is a concentrated solution remained after the sewage discharged from the bottom of the evaporator (9) is heated and evaporated; the other path enters a heat exchanger (6), and the heating medium is condensed water of steam condensed in the evaporator. The sewage is heated by two heat exchangers, the temperature of the sewage rises, the sewage is merged with circulating liquid from an evaporator (9) in a mixer (7), and then the sewage is sent to the evaporator (9) by a conveying pump (8). In the evaporator (9), the sewage is firstly heated to the saturation temperature under the corresponding salt content in the tube pass, then is continuously heated and evaporated, the salt content of the residual sewage after evaporation is increased, and the residual sewage is taken as concentrated solution to be discharged out of the evaporator (9) and enters a heat exchanger (5). Steam generated by sewage evaporation enters the compressor (10), is compressed into high-temperature and high-pressure steam by the compressor (10), and then enters the shell side of the evaporator (9) to serve as a heating medium to heat sewage of the tube side. The steam is condensed into condensed water, the condensed water is discharged from the evaporator (9) and enters the heat exchanger (6) to preheat sewage, the condensed water after heat exchange in the heat exchanger (6) enters the boiler (11) as boiler water supplement, the steam is heated into high-temperature and high-pressure steam in the boiler, and the steam is conveyed to the oil extraction system (12) through a ground pipeline and is injected into the underground.

Claims

1. An efficient oil field sewage treatment system, characterized by: the sewage treatment system comprises a sewage pretreatment system and an advanced treatment system; the pretreatment system comprises a gravity separator (1), a liquid storage tank (2), a water feeding pump (3) and a heat exchanger (4) which are connected in sequence; the advanced treatment system comprises a heat exchanger II (5), a heat exchanger III (6), a mixer (7), a delivery pump (8), an evaporator (9) and a compressor (10); the pretreatment system is used for carrying out primary treatment on oil field sewage, the sewage separated from the gravity separator (1) enters the liquid storage tank (2), the sewage in the liquid storage tank (2) enters the heat exchanger (4) through the water feeding pump (3), the sewage is preheated in the heat exchanger (4) by high-temperature produced liquid, and the high-temperature produced liquid after heat exchange returns to the gravity separator; the deep processing system comprises: dividing the sewage passing through the pretreatment system into two paths, wherein one path of the sewage enters a heat exchanger II (5), the sewage is heated again in the heat exchanger II (5), and a heating medium is a concentrated solution remained after the sewage discharged from the bottom of an evaporator (9) is heated and evaporated; the other path enters a heat exchanger (6), and the heating medium is condensed water of steam condensed in the evaporator; the temperature of the sewage is increased after the sewage is heated by the two heat exchangers, the sewage after heat exchange of the two heat exchangers is converged with circulating liquid from an evaporator (9) in a mixer (7), and then the sewage is conveyed to a tube pass of the evaporator (9) by a conveying pump (8); in the evaporator (9), sewage is firstly heated to the saturation temperature under the corresponding salt content in the tube pass, then is continuously heated and evaporated, the salt content of the residual sewage is increased after evaporation, the residual sewage is taken as concentrated solution to be discharged out of the evaporator (9) to enter a heat exchanger II (5), and the concentrated solution after heat exchange in the heat exchanger II (5) is sent to a gravity separator for continuous separation; steam generated by sewage evaporation enters the compressor (10), is compressed into high-temperature and high-pressure steam by the compressor (10), enters the shell pass of the evaporator (9), and is used as a heating medium to heat sewage of the tube pass of the evaporator (9); steam is condensed into condensed water in the evaporator (9), the condensed water is discharged from the evaporator (9) and enters the heat exchanger (6) to heat sewage, the condensed water after heat exchange in the heat exchanger (6) enters the boiler (11) as boiler water supplement, the condensed water is heated into high-temperature and high-pressure steam in the boiler, and the steam sent out by the boiler is conveyed to the oil extraction system (12) through a ground pipeline and is injected into the underground.

2. The system of claim 1, wherein the system is characterized in that: the pretreatment system carries out preliminary treatment on the oil field sewage, the oil field sewage is divided into water and silt of a lower layer and oil of an upper layer by using the gravity separator (1), the oil is collected from the left side of the gravity separator (1), the silt is discharged from the lower layer of the gravity separator (1), and the water enters the liquid storage tank (2) from the right side of the gravity separator (1).