Generator inner cooling water

Large and medium-sized units commonly used water - hydrogen cooling generator inner cooling water, selection of desalted water or condensate water as cooling medium. Cooling water quality to ensure the safe and economic operation of generating units of equipment is very important. In recent years, with the big capacity of subcritical, supercritical generating units put into operation, in order to ensure the safe operation of the equipment of power unit of generator inner cooling water, on the requirements of increasingly high quality, national GB / T12145 - 1999 " thermal power generating unit and steam power equipment ", for generator internal cooling water quality standards shall be as follows:

A ) of double water internal cooling generator and rotor independent cycle, in 25 degrees Celsius temperature, cooling water conductivity is less than 5μ S / cm, the concentration of copper is less than 40μ g / L, pH value greater than 6.8;

B ) unit power is 200 MW the following, the generator cooling water hardness ( water calcium and magnesium cations of the total concentration ) is less than 10μ mol / L, unit power is 200 MW and above, the generator cooling water hardness less than 2μ mol / L;

C ) steam turbine generator stator winding with independent closed circulating water system, the cooling water conductivity of less than 2μ S / cm.

2 in Shajiao A power plant in Shajiao C power plant generator inner cooling water system structure and operation condition analysis of 4.1 660 in Shajiao C power station MW generator inner cooling water system structure and operation condition

660 in Shajiao C power station MW generator inner cooling water system by inner cooling water tank, water pump, cooling device, filter and deionized small mixed bed. Generator inner cooling water treatment method is the generator of inner cooling water in closed cycle 7% ( flow is 8 m3 / h ) by deionized water cleaner for removing the anion and cation, achieves the purification water quality of small mixed bed treatment. The system design and installation of defects still exist in the original:

A ) deionized device for single chamber structure, simple internal structure, drift, resin leakage problem exists;

B ) deionized device filling is imported IRN160 composite resin manufacturers, according to information provided by IRN160 resin, running for about a year to replace, the working exchange capacity of small, short operation period, resin failure must be regenerated in vitro, higher operation cost;

C ) tank for detecting hydrogen leakage of compressed air in the CO2 will pollute the water quality, P H decreased;

D ) system monitoring means is not perfect, not to install the P H value detecting instrument.

3 generator inner cooling water super purification technology

Northwest Electric Power Test Research Institute of research and development of generator inner cooling water super purification technology, is available in small mixed bed treatment technology on the basis, realization of generator inner cooling water treatment technology innovation.

3.1 the general design of the system innovation

System design, in small mixed bed into the entrance, adding resin catcher, to ensure that the run or stop condition, the resin will not drain into a generator; water increased the respiratory component, effectively reduce the CO2 of air pollution to water quality, improve the water pH value; system configuration monitoring electrical conductivity and pH value measuring instrument.

3.2 mixed bed exchanger internal structure innovation

The a ) will be mixed bed single room double room structure structural modification, upcoming exchanger porous board divided into two upper and lower chamber, which is installed on the water cap of stainless steel, two upper and lower chamber is filled with a special ion exchange resin, two rooms can be independent, regeneration and backwashing, effectively solves the single chamber structure in backwash, because the failure resin with lower zero-failure high regeneration of resin layer, effect on effluent quality problems;

B ) exchanger inlet installed a water distributing device, the water inlet is uniformly distributed, reduce the flow generated by impact bias;

C ) the lower water outlet plate uniform drilling, hole equipped with special water cap of stainless steel, prevent resin leakage problem;

D ) bed with resin mixing nozzle, the pressure of water or air ejected from the nozzle resulting in the dynamic mixing resin, so that the two kinds of resin in the tank body is uniformly mixed, thereby to improve the water quality of effluent.

3.3 by using ion exchange resin

The use of special ion exchange resin to replace the ordinary type ion exchange resin. This special high intensity ion exchange resin by hydraulic separation, screening, acid-base salts and organic solvent after repeated treatment, after large doses of excellent pure reagents depth regeneration, inspection strict process optimization and treatment reduce the resin of low polymer content into resin. The optimization of special resin with high mechanical strength, uniform particles, after the test, the preferred cationic resin exchange capacity than before the preferably doubled, anionic resin exchange capacity than the preferred increased nearly 4 times, cycle of run is a small mixed bed 4～ 6 times.

3.4 examples of the use of

Generator inner cooling water of purification treatment technology in Qinling Mountains power plant 220 unit 330 in Pucheng power plant MW and MW unit's application, overall performance and technical indicators have reached very good results, and achieving long term maintenance free operation, high safety and reliability. The improved super purification treatment effluent index: the actual operation of the electrical conductivity, maintain in 0.06～ 0.1 μ S / cm, P H value in 7～ 7.9 between. Generator inner cooling water quality indicators: the actual operation of the electrical conductivity, in 0.1～ 0.5 μ S / cm, P H value in 7～ 7.9 between. According to the science and technology novelty search information, the technical performance indicators have reached international advanced level, to fill the current domestic and foreign large, medium-sized generators can not meet the generator inner cooling water conductivity and P H standard requirements of the technology gap.

4 at home and abroad of generator inner cooling water treatment method and existing problems

In order to improve the quality of inner cooling water in generator, current generating units at home and abroad generally take the anti-corrosion, purification methods are simply added in salt water or condensate operation mode, inner water cooling copper corrosion inhibitor, small mixed bed treatment method and two small mixed bed treatment method. These methods are difficult to solve in the actual production of internal cooling water conductivity and pH value of inner cooling water is the key technology to solve the existing small mixed bed treatment method of conductivity, copper ion indicators must be qualified, i.e. generator inner cooling water of pH not less than 7, and the stability is in 7 ～8 between; solve drift, small mixed bed resin leakage resulting effluent P H value caused by low cycle system acidic corrosion problems; solve small mixed bed resin exchange capacity of small, low mechanical strength, easy to break; realization of closed cycle system and prevent the water on circulating cooling water affected by impact of pollution problems, realize the long term stable operation and maintenance and other functions.

In Shajiao C power plant generator inner cooling water treatment using a small mixed bed, due to system and internal cooling water treatment system in the design and installation of defects, running from the testing data shows, although the generator inner cooling water conductivity can basically meet the requirements of GB and manufacturers, but the generator inner cooling water p H long-term instability in the state. In 2000 January 1 in Shajiao C power station generator inner cooling water at pH 8.06～ 8.64, February P H value in 8.06 ～8.23 between 2001 June, pH value in 6.08～ 8.76 ( in operation, generator No. 2 and No. 3 generator inner cooling water pH value is not stable ), indexes are difficult to meet the requirements of the national standard acidic corrosion, system safety. 4.2 200 in Shajiao A power station MW generator inner cooling water system structure and operation condition

200 in Shajiao A power station MW generator inner cooling water generator inner cooling water system also consists of inner cooling water tank, water pump, cooling device, filter and ion exchange cation bed form, but the system of ion exchange cation bed just deal with added salt, for closed cycle generator inner cooling water cannot get treatment, when the inner cooling water conductivity or pH value is not qualified, the desalted water, filling method, the inner cooling water conductivity and P H qualified. System design and installation are following a more serious defect:

A ) 200 MW unit hind of put into production, with high pH value ( P H not less than 8.5 above ) the condensed water for water supply, circulating generator inner cooling water conductivity has been high, maintain in 4 ～6 μ S / cm. With the GB / T12145 - 1999 GB to carry out, the original standard of inner cooling water conductivity is not larger than 5μ S / cm, now replaced by the conductivity is not larger than 2μ S / C M. In order to ensure the generator inner cooling water quality, come nearly two years uses less plus demineralized water for water supply, but the electrical conductivity is still in the 2.5～ 3.5 μ S / cm higher level. This way not only waste discharge s demineralized water, and difficult to reach the inner cooling water conductivity is not larger than 2μ S / cm gb.

B ) ion exchange cation bed set unreasonable, it can not play a role in the processing, purification and recycling of cooling water in action, in fact the ion exchange cation bed was never put into operation.

C ) ion exchanger has the advantages of simple structure, installed in the ordinary type of cation resin, resin breakage, leakage into the inner cooling water circulation system, causing water quality pollution.

5 transformation of generator inner cooling water treatment technology in Shajiao C power plant proposal

5.1 of generator inner cooling water treatment system should be revamped

Currently 660 in Shajiao C power station MW generator inner cooling water conductivity index can meet the standard requirements, but p H indicators to long-term instability, the presence of acidic corrosion safety hidden danger. In order to ensure the generator below the necessary technology, to meet the requirements of generator inner cooling water quality index:

A ) the single chamber deionized bed geminate chamber deionized ultra purification device, in order to improve effluent quality;

B ), exit into deionized bed with resin catcher, prevent resin leakage into the circulatory system;

C ) tank with CO2 absorbing component, reduce water pollution;

D ) system with pH monitoring instrument, improvement of generator inner cooling water in pH monitoring;

E ) using the domestic special anion, cation exchange resin, the resin operating replacement cycle extended by 1 years to 3 years, in order to reduce the cost of operation. 5.2 super purification technology by inner cooling water

200 MW unit in Shajiao A power plant generator inner cooling water conductivity was not up to the national standard requirements, there are more serious security risks. To ensure that the 200 MW generator inner cooling water conductivity is not larger than 2μ S / cm and P H value of long-term stability is in 7 ～8 between the national standard requirements, saving time discharge of waste a lot of water desalting, recommendations for inner cooling water system using water super purification technology to transform, in the generator inner cooling water circulation system with super purification device, to intercept water cycle a total of about 8% water deionization, replace the current row s way, cancel the replenishment system original cation exchanger. That is:

A ) in generator inner cooling water circulation system in the installation of purification treatment apparatus, equipment import and export resin catcher;

B ) with CO2 absorption water tank assembly;

C ) generator inner cooling water entrance is installed on the electrical conductivity and the online P H measuring instrument, super purification device is installed on the outlet of on-line conductivity meter;

D ) using the domestic special anion, cation exchange resin to replace the ordinary domestic resin, achieves the purification water quality, prolong the operation cycle, saving the purpose of operating costs;

E ) uses an ammonia demineralized water for water supply.