Method for reducing adhesion of ash in boiler and device for the same

a technology of adhesion and boiler, which is applied in the direction of lighting and heating apparatus, solid fuel combustion, combustion types, etc., can solve the problems of significant reducing heat absorption efficiency, drastic pressure change in the furnace, and occurrence of slagging or fouling, so as to reduce the adhesion of ash

Inactive Publication Date: 2012-07-12
KOBE STEEL LTD
View PDF5 Cites 9 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0035]In the method for reducing adhesion of ash in a boiler and the device for the same, the slag viscosity of the resultant solid fuel mixture at the predetermined atmospheric temperature is taken as the evaluation index, and the ash adhesion property is evaluated based on the slag viscosity. Then, the mixing ratio of the solid fuels is calculated so as to obtain the resultant solid fuel mixture having a slag viscosity that matches or exceeds the reference value at the predetermined atmospheric temperature, and the mixing ration is determined. As a result, even when various types of slid fuels including the low-grade coal are used as fuel, adhesion of ash in the boiler can be accurately predicted in a simple and convenient way, and accordingly reduced.

Problems solved by technology

The flowing ash adheres, in the course of discharge of the combustion gas, to wall surfaces of the furnace or the set of heat exchanger tubes, and deposits thereon, resulting in occurrence of slagging or fouling.
When the slagging or fouling occurs, heat transfer surfaces of the heat exchanger tubes are covered, thereby significantly reducing heat absorption efficiency.
Further, when a huge clinker produced on the wall surface or other parts by the slagging or fouling falls down, problems may arise, including drastic pressure change in the furnace, a damage to the heat exchanger tubes disposed on a furnace bottom, and blockage of the furnace bottom.
On the other hand, because the elements of the upper heat transfer unit provided in the upper part of the furnace are arranged at narrow intervals, the ash that adheres to anywhere in the upper heat transfer unit may cause significant changes in furnace pressure.
In addition, when the ash adhering to the heat exchanger tubes grows therebetween to an extent that a gas flow path is clogged with the ash, it becomes impossible for the combustion gas to flow through the set of heat exchanger tubes, which could cause an operational failure.
Further, in a region close to the burner, because the temperature in the vicinity of the wall surfaces of the furnace is elevated by radiation heat from combustion flames of fuel, the ash tends to easily adhere and melt onto the set of heat exchanger tubes having relatively low temperatures, which produces a problem in that growth of a huge clinker is facilitated.
Therefore, there is a problem in that a relationship between the indices and adhesion of ash described in Non-patent Literature 1 does not necessarily tend to match an actual relationship.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Method for reducing adhesion of ash in boiler and device for the same
  • Method for reducing adhesion of ash in boiler and device for the same
  • Method for reducing adhesion of ash in boiler and device for the same

Examples

Experimental program
Comparison scheme
Effect test

example

[0070]Hereinafter, an example of the method and device for reducing adhesion of ash in a boiler will be described.

[0071]In this example, an experiment in which a pulverized coal combustion test furnace (furnace inner diameter of 400 mm, in-furnace effective height of 3650 mm) was used, five types of pulverized coals, which have different compositions of ash components, were used under a condition that a total amount of heat input from city gas for heating was maintained constant at 149 kW was performed. In this example, the predetermined atmospheric temperature used for calculating the slag viscosity was set to 1300° C. Table 1 shows compositions of ash components in the five types of pulverized coals at 1300° C.

TABLE 1Coal ACoal BCoal CCoal DCoal EAsh contents [wt %-12.536.231.762.735.5DB]SiO2 [wt %-ash]69.856.9405253Al2O3 [wt %-ash]20.732327.8520.323.5CaO [wt %-ash]0.482.193.76.033.1TiO2 [wt %-ash]1.030.570.561.081Fe2O3 [wt %-ash]4.9511.819.9512.19MgO [wt %-ash]0.662.271.211.92.7N...

embodiment

MODIFICATION OF EMBODIMENT

[0075]Although the embodiment of this invention has been described above, the embodiment is provided merely as an illustrative example, and design details including specific configurations may be changed as appropriate. Further, operation and effect described in the embodiment of the invention are exemplified only as most preferable operation and effect obtained by the present invention, and the present invention is not limited to those described in the embodiment.

[0076]For example, although a scheme of determining the reference value based on the relationship between the previously measured slag viscosity and the ash deposition ratio has been described in the embodiment, the determination of the reference value is not limited to the scheme. In a case where a combustion test is conducted using a combustion test furnace or an in-service boiler while changing the viscosity of slag contained in fuel, the reference value may be determined from a slag viscosity ...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

A device for reducing ash adhesion in a boiler, includes: a calculator (9) which, in the case of mixing one or more types of solid fuels, calculates and determines the mixing ratio of the solid fuels so that the resultant solid fuel mixture has a slag viscosity not lower than a reference value at a predetermined atmospheric temperature; and fuel supply amount regulators (3a, 3b) which regulate the amount of the solid fuels to be supplied to the boiler based on the mixing ratio as described above. By using this device, ash adhesion in a boiler can be easily and accurately predicted and, therefore, ash adhesion can be reduced even in the case of using various types of solid fuels including a low-grade coal as fuel.

Description

TECHNICAL FIELD [0001]The present invention relates to a method for reducing adhesion of ash and a device for reducing adhesion of ash in a boiler which uses, as fuel, a solid fuel.BACKGROUND ART [0002]In conventional boilers using a solid fuel as fuel, pulverized coal obtained by crushing the solid fuel in a crusher is supplied as fuel along with carrier air to the boilers. Such a boiler includes a furnace for burning the supplied fuel by means of a burner or the like to generate heat, and a set of heat exchanger tubes arranged from an upper part to a downstream part of the furnace to cause heat exchange with a combustion gas directed to flow therein. The combustion gas generated in the boiler is discharged from a chimney. Here, the set of heat exchanger tubes is composed of an upper heat transfer unit in which a secondary heater, a tertiary heater, a final heater and a secondary reheater are arranged side by side at predetermined intervals in an upper part of the furnace, and a re...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
IPC IPC(8): F23C1/00F23N5/00F23K1/00
CPCF22B37/107F23J9/00F23J2900/01009F23N2041/10F23K2201/501F23N1/002F23N2021/10F23K1/00F23N2221/10F23N2241/10F23C1/00F23C99/00
InventorAKIYAMA, KATSUYAPAK, HAEYANG
OwnerKOBE STEEL LTD