2×600MW units of the first phase of the thermal power plant of the group are installed with two coal-fired boilers, two double-chamber four-field electrostatic precipitators for each boiler. The boiler pneumatic ash removal system is designed and installed by Beijing fortis with positive pressure concentrated phase double casing pneumatic ash conveying system.

 

A sending tank is installed under each dust bucket of the electric dust collector and coal economizer, and the inlet of each sending tank is equipped with a manual isolation valve and a pneumatic dome valve. The coarse ash of the economizer and an electric field is sent to the coarse ash warehouse through the coarse ash pipe; The fine ash of the second, third and fourth electric fields is sent to the fine ash storage house through the fine ash conveying pipeline. Each set of pneumatic ash removal system has three conveying pipelines, that is, all the ash conveying pipelines of #1 furnace are transported to #1 coarse ash storage and #3 fine ash storage through the switch valve on the top of the storage. All ash transport pipelines of #2 furnace are transported to #2 coarse ash storage and #3 fine ash storage through the switch valve on the top of the storage.

Ii. Reasons for transformation

 

In the boiler pneumatic ash removal pipe, the pipe expansion joint is used to compensate the pipe displacement caused by thermal expansion and cold contraction. Expansion joints can absorb axial and radial displacements of all connected equipment and ash removal pipes under operating and accident conditions.

 

Our factory boiler ash removal system ash delivery pipeline altogether 6 mother pipes, from the electric dust removal #1 bracket calculated to the ash warehouse each total length 1000 meters, each pipeline has 9 places, a total of 54 stainless steel waveform compensator. Due to pipe heat bilges cold shrink and pipeline deformation, since 168 h operation, compensator often occur deformation and breakage of ash leakage phenomenon, due to the original compensator expansion after repeated expansion and aging, metal fatigue, short service life, damage frequently, and the stainless steel corrugated compensator for precise die erste installation flange spacing requirements, the installation process is higher, maintenance time is long, slightly when the lead to reduce the load of the boiler, serious when outage led directly to the boiler. It has a great impact on the safety production and environment of our factory, and also affects the harmonious coexistence of enterprises and surrounding residents.

 

Third, the causes of the problem and the reasons for transformation

 

The main elastic element of stainless steel ripple compensator is stainless steel bellows, and its principle is to rely on the bellows expansion and contraction, bending to the pipe axial, transverse, angular compensation. It can compensate the axial, transverse and angular thermal deformation of absorption pipeline.

 

 

 

Due to its own characteristics and design reasons, the stainless steel ripple compensator in the dedusting pipe is frequently damaged and damaged, causing pollution to the surrounding environment. The main defects and problems are as follows:

 

1. The amount of compensation is limited, so the installation of pipes cannot be adjusted out of tolerance. When the pipeline compensation amount is too large, that is, non-recoverable damage, loss of compensation.

 

2, stainless steel ripple compensator often deformation, damage and ash leakage, maintenance costs.

 

3. Inconvenient maintenance and replacement. After the damage, there are no other maintenance and repair measures except replacement, and the replacement cost and maintenance time are relatively long. It is more difficult to repair and install the pipeline after it is displaced.it is necessary to reset the pipeline before installation. Once a leak is damaged, it can take a long time to replace it.

 

Four, telescopic principle and advantages

 

Pipe expansion (aka telescopic pipe), its working principle is: the expansion pipe inner and outer sleeve respectively by pipeline flange connection, the axial activities within the outer sleeve and the sleeve can, within the set of the 16 mn steel, wear-resisting coat in slip a stuffing box and gland, by dismantling the gland, can easily replace the packing box of the sealing material. Tighten gland nut for tight packing. A limited flange, a limited bolt and a nut are arranged on the inner sleeve. When the contraction quantity of pipe exceeds the limit, it can effectively prevent the stretching of expansion joint, play a role of stabilization and limit, and can also show the size of expansion quantity of expansion joint.

 

It has the following advantages: easy installation, large amount of expansion and contraction, strong and durable, no leakage, no plug, the flange spacing requirements are low, long service life, easy maintenance, can be replaced alone damaged parts, save maintenance costs and other characteristics.

 

V. renovation plan and effect

 

1. Check the whole ash transport pipeline and reinforce the expansion dead point.

 

2. Closely monitor the working condition of stainless steel corrugated expansion joint and measure its expansion amount under different working conditions;

 

3. Replace the stainless steel corrugated expansion joint with pipe telescopic (telescopic) after the leakage point occurs.

 

4. Closely monitor the working condition of pipe telescopic device (sleeve type) and measure its expansion amount under different working conditions;

 

5. Record the service time of newly installed pipe telescopic device (sleeve type).

 

Through the comparison of the actual operation effect after installation, the pipe telescopic device (sleeve type) is greatly superior to the stainless steel corrugated expansion joint in terms of the simplicity of installation, expansion and service life. The maintenance cost of ash transport pipeline in expansion joint is greatly reduced.