CN103743807A - Method for testing content of noncondensable gases in multi-effect evaporator - Google Patents

Abstract

The invention discloses a test method for accurately, efficiently and stably detecting the content of noncondensable gases in a multi-effect evaporating system. The test method is simple in operation, the water making energy consumption is effectively reduced and the water making cost is saved. The test method sequentially comprises the following steps: driving a secondary steam sample containing noncondensable gases generated by a multi-effect evaporator to pass through a condenser; pumping gases from a gas outlet of the condenser by a jet pump to obtain a gas-water mixture; heating the pumped gas-water mixture on line to vaporize water in the gas-water mixture; transferring obtained gases under the injecting effect of the jet pump to a mass spectrometer for detection; and calculating the content of noncondensable gases in the multi-effect evaporator according to a detection result of the mass spectrometer.

Description

The method of testing of multiple-effect evaporator non-condensable gas content

Technical field

The present invention relates to a kind of method of testing of multiple-effect evaporator non-condensable gas content, especially a kind of simple to operate, can accurately, efficiently, stably detect the method for testing of non-condensable gas content in multi-effect evaporation system.

Background technology

Horizontal pipe falling film evaporation has the advantages such as the inside and outside efficient phase transformation of little different transfer of heat, low discharge and pipe, and the desalting seawater through multi-effect evaporation based on horizontal pipe falling film evaporation technology has become the mainstream technology of following second generation seawater desalting plant.In Falling Film Evaporator of Horizontal Tube, be provided with horizontal tube bundle, thermal source flows through in horizontal tube, seawater is sprayed equably on horizontal tube bundle, outside pipe, forming falling liquid film flows, be subject to thermal evaporation simultaneously, after the steam producing collects, enter next single-effect evaporator as thermal source, part steam can part be met cold generation condensate water in horizontal tube bundle, and condensate water collects the rear product fresh water as desalinization.Because seawater is outside horizontal tube in falling film evaporation in generating steam, be attended by the inconduc solution suction phenomenon dissolving in seawater, when the secondary steam of the outer evaporation generation of pipe is together with non-condensable gas during the horizontal in-tube condensation at lower 1st effective evaporator, even if there is micro-non-condensable gas to exist, also can significantly reduce heat transfer property, the non-condensable gas content that is 0.5% as volumetric molar concentration in steam just can make heat transfer coefficient reduce by 50%.Therefore,, in order to improve heat transfer efficiency, just need to use special purpose device (ejector etc.) that the non-condensable gas in horizontal tube is extracted out.Yet, due to the low and mobile instability of non-condensable gas content, by conventional measuring technology, be difficult to measure the content of non-condensable gas, therefore prior art lacks the method for non-condensable gas content in effective measurement multiple-effect evaporation, conventionally be all the content that dependence experience is estimated non-condensable gas, therefore will produce and take out phenomenon, not only when extracting non-condensable gas out, take away excessive steam, and need to consume too much high-quality high pressure steam injection non-condensable gas, increased the energy consumption of water processed, certain low-temperature multi-effect evaporation seawater desalinization factory that the fresh water yield of take is 10000 tons/day is example, high pressure steam amount for the consumption of injection non-condensable gas has accounted for 10% of wastage in bulk or weight quantity of steam.

Summary of the invention

The present invention is in order to solve the existing above-mentioned technical matters of prior art, provide a kind of simple to operate, can accurately, efficiently, stably detect the method for testing of the content of non-condensable gas in multi-effect evaporation system.

Technical solution of the present invention is: a kind of method of automatic test multiple-effect evaporator non-condensable gas content, is characterized in that carrying out as follows successively:

A. the secondary steam sample that contains non-condensable gas producing in multiple-effect evaporator is passed through to condenser;

B. the gas outlet of using ejector injection suction cooler, obtains air-water mixture;

C. the air-water mixture of on-line heating institute injection sucking-off, makes the water vapor in air-water mixture;

D. under the ejector action of ejector, resulting gas being inputed to mass spectrometer detects;

E. according to mass spectrometer testing result, calculate non-condensable gas content in multiple-effect evaporator.

The present invention is simple to operate, can accurately, efficiently, stably detect the content of non-condensable gas in multi-effect evaporation system, can monitor in real time the non-condensable gas content producing in low-temperature multi-effect evaporation seawater desalinization process, avoid taking away excessive steam when extracting non-condensable gas out, also can avoid consuming too much high-quality high pressure steam injection non-condensable gas, reduce the energy consumption of water processed, saved water producing cost.

Accompanying drawing explanation

Fig. 1 is the structural representation of embodiment of the present invention equipment therefor.

Fig. 2 is the structural representation of embodiment of the present invention condenser used.

Embodiment

Embodiment of the present invention equipment therefor is provided with two-stage tandem condenser 21, and two-stage tandem condenser is in series by first order condenser 1 and second level condenser 7 as shown in Figure 2; First order condenser 1 and second level condenser 7 are equipped with steam inlet 2, coolant outlet 3, cooling water inlet 4, gas outlet 5, condensate outlet 6.

The gas outlet 5 of two-stage tandem condenser 21 joins with the suction inlet of ejector 24 by pipeline 22, valve 23 etc., on pipeline 22, be provided with electrical heating wire 25, pipeline 22 through electrical heating elements 25 joins by lateral 26 and mass spectrometer 27, on lateral 26, also electrical heating wire can be set.

The course of work:

A. the secondary steam sample that contains non-condensable gas multiple-effect evaporator being produced enters into case side by the steam inlet 2 of first order condenser 1, chilled water enters into condenser tube side by cooling water inlet 4, most of secondary steam is in case side condensation, the bottom that condensed fluid accumulates in case side is flowed out by condensate outlet 6, chilled water is flowed out by the coolant outlet 3 of condenser lower end, the secondary steam not condensing and non-condensable gas are flowed out by the gas outlet, upper end 5 of first order condenser shell side and the air intake opening by second level condenser 7 enters into and in case side, continues condensation, condensed fluid is flowed out by condensate outlet, non-condensable gas is flowed out by the non-condensable gas outlet of second level condenser, to greatest extent that non-condensable gas is separated with steam,

B. with the gas outlet 5 of ejector injection suction second level condenser 7, sucking-off is with the non-condensable gas of a small amount of condensed fluid, i.e. air-water mixture, and air-water mixture enters pipeline 22 under the driving of ejector water under high pressure;

C. with the non-condensable gas of a small amount of condensed fluid electrical heating wire 25 of flowing through in pipeline 22, a small amount of condensed fluid vaporization wherein becomes water vapour, forms the gas that non-condensable gas and water vapour mix;

D. under the ejector action of ejector, a part of gas is exported through ejector, and another part gas inputs to mass spectrometer and detects, and draws water vapour and non-condensable gas content separately in the mass spectrometer portion gas of flowing through; Due to by contained a small amount of condensed fluid vaporization in non-condensable gas, thereby eliminate the fluctuation that causes due to the gas-liquid two-phase interphase interaction impact on non-condensable gas flow measurement;

E. due to the portion gas through ejector output and the ratio that inputs to the portion gas that mass spectrometer detects can set by by-pass valve control, therefore according to mass spectrometer testing result, can calculate the non-condensable gas total amount of discharging from gas outlet, if the secondary steam sample that the contains non-condensable gas condensed fluid flow that condensation obtains in two-stage tandem condenser producing in multiple-effect evaporator is W, the non-condensable gas total amount of measuring is Q, non-condensable gas that multiple-effect evaporator produces is Q/(W+Q with the ratio of the secondary steam that contains non-condensable gas), thereby can effectively measure non-condensable gas content in multiple-effect evaporation.

Claims (1)

1. a method of testing for multiple-effect evaporator non-condensable gas content, is characterized in that carrying out as follows successively:

A. the secondary steam sample that contains non-condensable gas producing in multiple-effect evaporator is passed through to condenser;

B. the gas outlet of using ejector injection suction cooler, obtains air-water mixture;

C. the air-water mixture of on-line heating institute injection sucking-off, makes the water vapor in air-water mixture;

D. under the ejector action of ejector, resulting gas being inputed to mass spectrometer detects;

E. according to mass spectrometer testing result, calculate non-condensable gas content in multiple-effect evaporator.

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