CN1351966A

CN1351966A - Composite water deoxidizing agent for wet steam generator

Info

Publication number: CN1351966A
Application number: CN 01135241
Authority: CN
Inventors: 王允正
Original assignee: YUHUA CHEMICAL PLANT BINZHOU SHANDONG PROV
Current assignee: YUHUA CHEMICAL PLANT BINZHOU SHANDONG PROV
Priority date: 2001-12-11
Filing date: 2001-12-11
Publication date: 2002-06-05

Abstract

A composite water-deoxidizing agent as a kind of compositve water treating agent consists of ammonium sulfite 15-40 wt% and organic amine 0-10 wt% beside the rest of water. It is used in water treatment of steam boiler and can reduce oxygen content in water from 0.1-0.4 mg/l to less than 0.01 mg/l and raise water pH value from 7.0-7.5 to 8.3-9.0. The treated water has no corrosion to pipeline and no damage to oil layer. Its ammonium sulfite may be produced by absorbing SO2 in waste gas with ammonia water, and this can protect environmental and reduce water treating cost. The composite water deoxidizing agent of the present invention has high deoxidizing effect and reduced corrosion to pipeline.

Description

Composite water deoxidant for wet steam generator

Technical Field

The invention provides a composite water treatment agent, in particular to a deoxidant.

Background

In order to recover thick oil, crude oil production enterprises need to inject wet steam into the well. The wet steam generator (steam injection boiler for short) is a high-temperature and high-pressure equipment, its operating pressure is up to 17.2MPa, and it can produce wet steam whose dryness is 80%. The water quality requirement of the water for steam production is very strict, and the key indexes are as follows: the hardness is zero milligram per liter, the oxygen content is less than 0.01mg/l, and the pH value is 8.3-9.0. Because the water quality can not meet the requirement, the pipeline is seriously corroded, and the crude oil production enterprises generate the pipe explosion accidents of the furnace pipe and the steam injection pipe network for many times, thereby not only causing serious economic loss, but also bringing great harm to the personal safety. The main reasons are that the deoxidant is not suitable, the oxygen content of the water quality of the supplied water greatly exceeds the standard, and the PH value is low.

The water quality treatment process and equipment of steam injection boilers are mostly introduced into the United states technology at first. In the water quality treatment process abroad, sodium sulfite is mostly adopted to deoxidize the supplied water, and in various oil fields in China, sodium sulfite is also adopted to deoxidize. And the foreign steam injection boiler using sodium sulfite to remove oxygen is mostly established under the shallow low-pressure steam injection condition. The disadvantage of using sodium sulfite as deoxidant in domestic oil field is that when the oxygen content in water is less than 1mg/l, more sodium sulfite excess is needed, and when the pressure exceeds 7MPa, the excess sodium sulfite is easy to decompose to produce compounds such as hydrogen sulfide and sulfur dioxide with strong corrosivity, and produces acid corrosion to pipelines, and the decomposed sodium ions form strong alkaline substances, so that it not only can easily cause "alkali-brittle" corrosion to steel pipelines and equipment, but also can corrode stratum after being injected into underground, and can cause corrosion collapse in near zone and coagulation blockage in far zone, and reduce stratum permeability, and can affect crude oil recovery ratio.

Disclosure of Invention

The invention aims to solve the technical problem of providing a composite deoxidant for water quality of a wet steam generator, which can effectively deoxidate water for steam generation and prevent pipelines from being corroded.

The invention is realized in this way, the moisture steam generator water quality composite deoxidant, it is made up of ammonium sulfite, organic amine and water, its proportion is: 15-40% of ammonium sulfite, 0-10% of organic amine and the balance of water.

The preferred proportion of the composite deoxidant for the water quality of the wet steam generator is as follows by weight: 16-39% of ammonium sulfite, 0.1-9% of organic amine and the balance of water.

The organic amine is ethylenediamine or/and triethanolamine.

The water quality composite deoxidant is used for treating water for steam production of a steam injection boiler and reaches the following indexes: the residual oxygen in water before entering a furnace is reduced to less than 0.01mg/l from 0.1-0.4 mg/l, the pH value of water is treated to 8.3-9.0 from 7.0-7.5, reaction products after water treatment are free of precipitation, pipelines are free of corrosion and do not damage oil layers, ammonium sulfite can adopt products obtained after ammonia water is used for absorbing SO2 in waste gas, waste utilization is achieved, the national environment-friendly requirement is met, water treatment cost is low, production and manufacturing are simple and convenient, the oxygen removal process is convenient to operate, and the effect is stable.

The invention is further illustrated below.

The organic amine in the composite oxygen scavenger of the present invention may also be an organic amine such as cyclohexylamine, benzylamine, morpholine, octadecylamine, hexadecylamine, dioctadecylamine, etc.

After the composite water oxygen scavenger is used, ammonium sulfite reacts with oxygen in water to generate ammonium sulfate, and the ammonium sulfate can react with carbonate and bicarbonate in the water to generate gaseous substances such as ammonia, carbon dioxide and the like. Not only can reduce the generation of hydroxyl ions and avoid the excessive enhancement of water quality alkalinity, but also can decompose carbonate and bicarbonate radical to properly enhance the water quality alkalinity. Thereby removing most of the oxygen and maintaining the PH in the proper range.

The reaction of ammonium sulfite in water is as follows:

the products of the further reaction enter the gas phase due to the CO of the product₂The catalyst is acidic, NH3 is basic, and the catalyst can be recovered to neutral salt at any time along with the acidity and the basicity of NH3, and does not corrode equipment, namely

Or

。

In the liquid phase, due to CO₂Is removed and its conversion to hydroxide is avoided at high temperature and high pressure.

The organic amine is added into the composite oxygen scavenger, and the organic amine volatilizes at different speeds in the process of gradually increasing the water temperature to form a protective film on the surface of steel so as to reduce the corrosion of possible acid gas. The organic amine can not react with the silicon dioxide after entering the stratum, and the corrosion effect is not generated. Because the reaction speed is high, the oxygen scavenger does not need to be excessive, and the defect of using sodium sulfite is basically overcome.

The composite deoxidant is produced through adding ammonium sulfite, organic amine and water in certain proportion into enamel reactor and stirring at normal pressure and 60 deg.c below.

In order to increase the reaction speed, the composite oxygen scavenger of the invention can be added into the steam-producing water before the water-water heat exchanger after most of residual oxygen is removed by the thermal oxygen remover, and the water temperature is about 104 ℃ at the moment.

Example (b): the composite deoxidant prepared from 27% of ammonium sulfite and the balance of water is added into the steam-producing water before the water-water circulator after most of residual oxygen is removed by a thermal deaerator, and the addition amount is 28ppm in the water. After treatment, the oxygen content is reduced from 0.1mg/l to 0.003-0.004 mg/l, the excess amount of sulfite is 1.6-3.0 mg/l, the PH value of wet steam generated by a steam injection boiler is 10.11, and the pH value is reduced compared with that of the wet steam which is not added with an oxygen scavenger by 11.05.

The following are specific proportions of the composite oxygen scavenger in the invention by weight:

35% of ammonium sulfite, 3% of organic amine and the balance of water;

18% of ammonium sulfite, 2% of organic amine and the balance of water;

40% of ammonium sulfite, 1% of organic amine and the balance of water;

23% of ammonium sulfite, 9% of organic amine and the balance of water;

36% of ammonium sulfite, 0.3% of organic amine and the balance of water.

The amount of the composite oxygen scavenger in the steam-generating water is the same as that of the composite oxygen scavenger prepared from 27% of ammonium sulfite and the balance of water in the previous embodiment after being converted by concentration.

The composite oxygen scavenger greatly reduces the oxygen content of water for steam production, and prevents the strong corrosion of residual oxygen (dissolved oxygen) to pipelines, so that no pipe explosion accident occurs until the composite oxygen scavenger is tried on a plurality of steam injection boilers in 7 months in 1997.

Claims

1. The composite deoxidant for water quality of the wet steam generator is characterized by comprising ammonium sulfite, organic amine and water, and the weight ratio of the composite deoxidant is as follows: 15-40% of ammonium sulfite, 0-10% of organic amine and the balance of water.

2. The composite oxygen scavenger for water in a wet steam generator of claim 1, wherein the composition is, by weight: 16-39% of ammonium sulfite, 0.1-9% of organic amine and the balance of water.

3. The composite oxygen scavenger for water in a wet steam generator of claim 1 or 2, wherein the organic amine is ethylenediamine or/and triethanolamine.