DD216777B1 - METHOD FOR THE UNLIMITED DETECTION OF CHANGING PROPERTIES OF THE SPINY BED MATERIAL - Google Patents

Description

For this 1 page drawing

Field of application of the invention

The invention relates to a method for the inertia-free detection of variable properties of the bed material in the combustion of ballast fuels, especially alkaline fuels, in fluidized bed combustion for subsequent control variables of the combustion process.

Characteristic of the known technical solutions

The combustion of ballast-rich and alkali-containing fuels in fluidized bed combustion leads due to the alkali content, analytically detected as Na ₂ O + K ₂ O, to chemically-physically variable properties of commonly used bed material, such as sand, cold stone chippings, corundum, magnesite, etc. At low combustion temperatures, 780 900 ^° C., in an oxidizing atmosphere, at working speeds of 0.8 m / sec and at bed sizes of 0.2 to 4.0 mm, which are preferably used for the combustion of saline fuels in the fluidized bed , the monitoring and control of the combustion process is carried out by:

- Flue gas analyzes CO ₂ , CO, O ₂

- Temperature measurement in the fluidized bed (multiply) and above the fluidized bed (multiply)

- Differential pressure measurement of the inflow plate + fluidized bed and possibly several times in certain heights of the fluidized bed

Monitoring of Average Grain Fraction of Bed Material by Intermittent Sampling and Examination Experience has shown that reaction products of minerals of the fuel ash and the additive are deposited on the bed material despite the high intensity of the fluidization of the bed material. In order to prevent coarsening and sticking / crusting of the bed material, mass exchange must be organized by discharging the combustion residues, additive reaction products and bed material. The replacement must be carried out in sizes which ensure that the limit value of the components is not exceeded, which leads to sticking together.

The accumulation of minerals on the bed material leads to a change in the physical properties of the bed material.

Since it has been found that the threshold value / threshold value which leads to the instability of the fluidized bed is also heavily dependent on the fluidization state, the temperature level, the material-analytical parameters of the bed material and the chemistry of the fuel gas, the usual measures are not suitable for sufficiently monitoring the combustion process and to regulate.

Object of the invention

It is an object of the invention, inertia, to obtain the primary information from the physical Bettverhaltsn to continuously below the limit value in optimized bed replacement and the fluidized bed for saline fuels and to stabilize economically.

Explanation of the essence of the invention

The invention has for its object to detect the physical changes in the bed material inertia by Druckpulsationsmessungen and to use as a manipulation size.

According to the invention, the object is achieved by measuring the pressure pulsation (amplitude and frequency) as an expression of the actual physical state of the bed material.

It has been found that the qualitative change in the bed material takes place in a very short time. Therefore, a measured variable is to be recorded, which reflects the changes without a picture. The suitable measuring variable is the pressure pulsation, the change of which as a controlled variable enters into the combustion process.

embodiment

An exemplary embodiment is shown greatly simplified in FIG. 1. On you; Representation of immersed in the fluidized bed and arranged in Nachbrennraum heating surfaces is omitted.

In the fluidized-bed reactor (1), the fluidized bed (2) is built up via the distributor plate (3), the height of which in the fluid state is limited by the bed material overflow (6). The vortex and combustion air (4) and the mixture of fuel and additive (5) is fed via lines to the combustion reactor / metered.

The coal application takes place via the flue gas analysis (8) as a degree of goodness and on the performance requirement.

The additive dosage CaCO ₃ takes place after the SO ₂ measurement (8) and monitoring of the bed material (11).

The excess of bed material is removed via the Bettuberlauf / deduction (6) from the combustion reactor.

The fluidization state in the combustion reactor is measured by the temperature measurements (9), differential pressure measurements (10) and checked by sampling of bed material (11).

It has been found that by a pressure pulsation measurement the actual physical state of the bed material can be measured by amplitude and frequency. By means of a pickup (12), the amplitude and frequency in the fluidized bed is detected, amplified in an amplifier (13) and can be made visible on an indicator (17). By switching on a recorder (16) and a memory (15) the possibility of a current evaluation is given.

It is necessary to keep the probe free (18) and to filter out the resulting overlaps of pressure pulsations.

Claims (3)

1. A method for detecting variable properties of the fluidized bed material, in particular in the combustion of alkaline fuels characterized in that the changing physical properties of the bed material with increasing bed load with the aid of the amplitude and frequency of the pressure pulsation are detected and the change in the measured pressure pulsation inertia than Control variable for combustion control is available. 2. The method according to claim 1, characterized in that the required mass exchange of the bed material as a manipulation variable for the combustion control according to the change of * Physical fluid state quantities due to mineral and alkali contaminants indicated by change in pressure pulsation. 3. The method according to claim 1 and 2, characterized in that an optimization of the mass exchange of bed material by a permissible limit of the change of the pressure pulsation is determined for the respective fluidized bed and upon reaching this limit, the mass exchange takes place to a sufficient extent, so that a Stabilization of the fluidized bed is achieved.