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Boiler Parts Renovation Technology

一、 the light pipe economizer to expand the heating surface transformation technology

The economizer utilizes the flue gas heat from the tail of the boiler to heat the feed water, which can reduce the exhaust temperature, improve the boiler efficiency, improve the working conditions of the drum, and is the necessary convection heating surface of the boiler. As the economizer is arranged in the boiler flue gas flue gas with low temperature area, in the operation prone to fly ash wear, low temperature corrosion and fouling and so on. In recent years, due to changes in the coal supply market, most coal-fired power plants have various coal channel, coal quality instability or even decline, fuel ash increased, resulting in some power plant boiler economizer heating surface wear , which cause g great threat to the unit's safe and stable economic operation.

Economizer application of the surface heating surface can reduce the heating surface of the fly ash wear and tear, while the heating surface can be compact, reduce ventilation resistance and fluid flow resistance and metal consumption. The use of extended heating surface in the boiler with the economizer to transform, in order to existing installation space conditions, to ensure the same heat transfer effect, or even improved. Reduce the flue gas flow rate, reduce wear, avoid fouling and low temperature corrosion, is one of the most effective measures to improve the use of boiler economizer heating surface stability.

Economizer application of the surface expansion of the main form is from light pipe economizer to finned tube economizer, from light pipe economizer to H-finned tube economizer, from light pipe economizer to membrane economizer.

A), light pipe economizer to finned tube economizer transformation technology

Spiral finned tube adopt high-frequency welding method, the strip along the spiral trajectory welded to the formation of the light pipe. Compared with the annular finned tube, through the fin material of the winding process and high-frequency welding, can make the fins and the base pipe fusion, the contact resistance is similar to 0, can withstand alternating heat Stress, no deformation after welding, which will not weaken the base pipe pressure capacity, good for  conducive to heat from the ribs to the base pipe wall transmission. A serpentine tube with a spiral finned tube (no ribs in the elbow section) is used as the economizer heating surface.

If the height of the economizer is limited, a smaller diameter of the base pipe is required.

The heat transfer coefficient of the extended heating surface is smaller than that of the light pipe having the same base pipe diameter. The heat transfer coefficient of the fin tube is only 82% ~ 88% of the same tube diameter heat pipe heat transfer coefficient; spiral finned tube heat transfer coefficient is smaller, only the same diameter of the same tube diameter tube heat transfer coefficient of 45% to 49 %. At the same time: the heat transfer coefficient of various types of heating surface decreases with the increase of the diameter of the base pipe. More importantly, as the diameter of the base pipe increases, the amplitude of the heat transfer coefficient decreases as compared to the heat transfer coefficient of the same heating pipe and the same diameter of the base pipe.

The heat transfer coefficient and the area of heat transfer area of the heating surface can properly reflect the influence of the structural characteristic change on the convective heat transfer

The heat transfer energy efficiency of all extended heating surfaces is increased compared with that of the light pipe, but the heat transfer energy efficiency of the different forms of extended heating surfaces is different. Spiral finned tube due to its heating surface expansion coefficient, so despite the smallest heat transfer coefficient, but the heat transfer efficiency is still the largest.

Case: Chengwu Jin'an thermoelectric light pipe economizer transformation for the spiral economizer, running well.

二). light pipe economizer to change the H-fin tube economizer transformation technology

Ultra-wear-resistant H-type finned tube, also known as H-type finned tube, also known as butterfly tube, it is the middle of the two pairs of arc steel plate symmetrically welded together with the light pipe to form fins (ribs or Butterfly), the front shape quite like the letter "H", so called H-fin tube

1, excellent wear resistance

The wear rate of the pipe is proportional to the coefficient of unevenness of the flue gas velocity KV3.33, which is proportional to the unevenness coefficient of the fly ash concentration.

The H-type finned tube economizer is arranged in a row, and the H-fin fins the space into several small areas, and the flow is equalized to the flow, and the economizer with the misaligned arrangement, the economizer , The longitudinal fins compared to the other conditions in the same circumstances, the wear life of 3-4 times higher.

Flue gas side baffle protection elbow part. 

2, fouling reduced

The formation of fouling occurs in the back and face of the tube. Pipe staggered layout easy to flush the tube, the back fouling less. For the layout of the pipe, because the air is not easy to rinse the back of the tube, the pipe in terms of arrangement of fouling than the wrong column.

H-fin fins because the fins in the pipe is not easy to fouling on both sides, and the air flow straight, the direction of the air does not change, the fin is not easy to fouling.

3, space is compact, reduce the cost

The tube group is very compact and reduces the height of the tail smoke.

The overall weight greatly reduced, reducing the suspension system load.

Reduce the cost of the economizer and the overall boiler.

4, to reduce the smoke side resistance

Reduce the fan operation and investment costs.

Case: Huludao Fangda chemical light pipe economizer transformation for the H-finned tube economizer, running well.

三), light pipe economizer change to membrane economizer transformation technology,

Membrane type economizer is made by welding finned tube, rolling fin tube or welded with steel plate in the adjacent pipe composed of the economizer.

Its main advantages are:

(1) to save metal materials, usage of thin steel plate in part to replace the pipe, so that the pressure components and total metal consumption are reduced.

(2) Long low tube height is generally comparable to the height of the tube of the economizer, about 28 or so, which is favorable for the arrangement of the tail heating surface.

(3) to enhance the rigidity of pipe row, simplify the support structure, easy to install.

(4) reduce the fouling and wear of the economizer.

(5) reduce the economizer water side and smoke side, the general side of the smoke can be reduced , decline in plant electricity

Case: Zaozhuang far-paper light pipe economizer for the film-type economizer, running well.

二, the air preheater anti-corrosion anti-blocking technology

The air preheater is the tail heating surface of the boiler, but both the industrial boiler and the power plant boiler, there is a common problem for air prehater - serious low temperature acid corrosion and blocking ash, especially burning higher sulfur Fuel is particularly prominent, seriously affecting the safety and economic operation of the boiler.

At present, the national requirements for nitrogen oxide emissions increasingly stringent, especially the installation of SCR denitrification device on the impact of air pre-discharge is more prominent. The main reason is the corrosion of ammonium bicarbonate and adhesion. Hydrogen sulfate in the 145 ℃ -208 ℃ temperature range for the liquid, liquid ammonia sulfate to capture fly ash is very strong, with the flue gas in the fly ash particles combined, attached to the preheater heat transfer element to form molten salt Like the opportunity to cause the air preheater corrosion, blocking ash. Ammonium hydrogen sulfate in the dust together with the air conditioning device on the heat exchanger, not only reduce the heat transfer effect, but also in the low temperature of the air preheater low temperature corrosion, while causing air preheater fouling, resulting in air Serious blockage.

Modification measures:

1, change the original air preheater into enamel pipe air preheater, for different furnace type, flue gas composition and air preheater operation analysis and diagnosis, adjust the enamel formula, effectively solve the problem of low temperature corrosion and blocking ash.

2, through the transformation of air preheater form, optimize the air preheater pitch and flue gas flow rate, reduce the air preheater fouling problem:

The air preheater tranformed from horizontal to vertical, this can be used to improve the flue gas flow rate without increasing the side resistance of the flue gas, increase the capacity of the air preheater and install the anti-wear sleeve at the inlet end of the flue gas, Anti - wear ability

Air preheater from vertical to horizontal, applying in the garbage furnace, biomass furnace and other fouling more serious, appropriate to increase the lateral pitch, adjust the flue gas flow rate, reduce the fouling. The use of smooth structure, easy to fouling clean. After the transformation of horizontal pipe box generally use small diameter tube, enhanced heat transfer efficiency, while the horizontal tube single tube's replacement is more convenient (can be used flexible seal);

3, for the installation of flue gas recirculation device boiler air preheater and GGH, the use of internal and external double enamel technology to enhance the service life.

4, on the horizontal air preheater cold section, to take special anti-corrosion measures to enhance the life of air preheater.

5, optimize the structure of the air preheater, reduce the bias and the key parts of wear and tear. Through the calculation of reasonable selection of shock absorber installation location, reduce the resonance.

Case

Shandong Zhenghe Thermal Power Co., Ltd. 220T Pulverized Coal Mine Vertical Horizontal

Anqing Wanneng Zhongke Electric Power Environmental Protection Co., Ltd. Biomass Boiler from Vertical to Horizontal transformation

Guangxi Baise Yinhai Power Generation Co., Ltd. 2 * 480T Boiler Vertical Pipe Box Optimization Design (Pipe Diameter Adjustment)

Yantai Qingquan Industrial Co., Ltd. 130T boiler mixed with sludge after the air preheater vertical to horizontal