JPH0412918B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a highly concentrated coal-water slurry, and more particularly to a method for controlling slurry moisture in a method for producing a coal-water slurry in which the slurry moisture is controlled.

[Conventional technology]

The conventional coal-water slurry production method uses a wet ball mill to wet-pulverize crushed coal with a dispersant consisting of water and a surfactant to form a slurry, producing a coal-water slurry with a coal concentration of approximately 60% by weight or more. do. In addition, in order to cool the coal-water slurry whose temperature has increased due to the heat of grinding during wet grinding,
It has been proposed to perform heat exchange with an air stream when separating and removing coarse particles in a coal-water slurry (for example, Japanese Patent Laid-Open No. 60-8393,
60-13887, Japanese Patent Application No. 61-212011, etc.).

In the production of coal-water slurry, variations in water content, that is, coal concentration, among the properties of coal-water slurry, have a large effect on the process. That is, it can have a significant influence on the pulverization properties in a wet mill, flow properties such as fluidity and stability, as well as fuel properties such as calorific value and thermal efficiency, atomization in a burner, and combustion properties.

To eliminate the above effects, the slurry moisture control method in the conventional coal-water slurry manufacturing method involves adjusting the amount of coal and water supplied to the wet mill under ratio control to obtain the required slurry moisture. In addition, the above-mentioned supply amounts were adjusted by manually making corrections for the amount of evaporation of slurry moisture caused by the temperature rise due to the heat of pulverization of the coal-water slurry during the wet pulverization process. . In addition, slurry water content has also been controlled by measuring the slurry water content using an industrially applicable slurry concentration meter and adjusting the above-mentioned supply amounts of coal and water.

[Problem to be solved by the invention]

However, in the slurry moisture control method in the conventional coal water slurry manufacturing method described above, the slurry moisture is measured off-line and correction is made for the amount of evaporation of the slurry moisture, but the amount of evaporation of the slurry moisture is also subject to many complicated fluctuation factors. Therefore, it is difficult to accurately detect the amount of evaporation, and it is difficult to accurately control the slurry water content. In addition, even if slurry moisture is detected using a slurry concentration meter and the amount of coal and water supplied is adjusted through feedback control, it is difficult to control slurry moisture appropriately for processes under complex fluctuating factors. There was a problem.

The present invention solves these conventional problems by reliably determining the amount of evaporation of slurry water using a simple method, and making it possible to accurately control slurry water with a high accuracy rate. The purpose is to provide superior slurry moisture control in a coal-water slurry manufacturing method.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a slurry in a method for producing a coal-water slurry in which coal is wet-pulverized with water and a dispersant in a wet mill to form a slurry, and the slurry whose temperature has increased due to the heat of crushing is cooled by an air flow. This is a moisture control method that detects the humidity change in the air flow before and after the slurry comes into contact with the air flow, calculates the amount of moisture evaporation, and controls the slurry moisture by controlling the amount of water supplied to the wet mill. This is what I did.

[Effect]

The present invention has the following effects due to the above configuration. That is, the slurry whose temperature has increased due to the heat of grinding due to wet grinding is cooled by air flow in a cooling chamber surrounding the flow path, and at that time, the change in humidity of the air flow is detected before and after the slurry comes into contact with the air flow. Since the water evaporation amount of the slurry can be calculated using the above method, the amount of water supplied to the wet mill can be manipulated to obtain the required water content of the slurry product. It is possible to accurately control slurry moisture with high accuracy even under the influence of various fluctuation factors.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a configuration according to an embodiment of the present invention.

In Fig. 1, 1 is a coal storage tank that stores crushed coal 2, 3 is a metering coal feeder that feeds coal 2 by metering, and 4 is a wet ball mill that wet-pulverizes coal 2 together with water and a dispersant. . 5 is a water supply pipe with a pump 6; 8 is a dispersant supply pipe with a pump 9;
It is connected to the entrance. Reference numeral 10 indicates a slurry produced by the wet ball mill 4, and reference numeral 11 indicates a vibrating sieve for separating and removing coarse particles of coal contained in the slurry 10. 12 is a vibrating sieve 11
The cooling chamber 12 is provided with an air inlet and an air outlet, respectively, for cooling the slurry that has passed through the cooling chamber 12 with an air flow. An inlet air pipe 13 is provided at the air intake of the cooling chamber 12, and an outlet air pipe 26 is provided at the air outlet. He is trying to make air flow into the cooling chamber 12 by the blower 30. 22 indicates a slurry pipe, and the slurry 20 cooled in the cooling chamber 12 is fed to the next step by a pump 21.

The coarse particles 17 separated by the vibrating sieve 11 are fed by a transport means, for example, a pump 18, and are returned to the wet ball mill 4 as a coarse particle slurry 19 to be used for slurry production. The inlet air pipe 13 is provided with a hygrometer 14, a flow meter 15, and a thermometer 16, respectively, and are used to detect the state value of the inlet air flow. The outlet air pipe 26 is provided with a hygrometer 27, a flow meter 28, and a thermometer 29, respectively, and are used to detect the state value of the outlet air flow. The slurry pipe 22 is provided with a slurry concentration meter 23, a flow meter 24, and a thermometer 25, which are used to detect the properties of the slurry product.

Reference numeral 31 indicates a main controller, and 32 indicates a setting command, into which the state values of the inlet air flow and outlet air flow and the measured values of the properties of the slurry product are respectively input. The main controller 31 calculates the amount of moisture contained in each air stream based on the measured values of humidity, flow rate, and temperature in the inlet air stream and outlet air stream, as set command values including the moisture content of the slurry product. Furthermore, the amount of moisture transferred from the slurry to the air flow by the moisture amount subtraction process, that is, the amount of moisture evaporated is calculated. The main controller 31 outputs a signal 34 to the water supply flow rate control valve 7, and at this time, the water supply amount is set so as to be corrected based on the water evaporation amount. Output signal 33
sets the amount of coal to be fed to the metering feeder 3. In the water supply flow rate control valve 7 and the metering feeder 3, the water supply flow rate and the coal supply amount are operated and controlled in response to the above-mentioned water supply flow rate deviation and coal supply amount deviation.

Next, the operation of the above embodiment will be explained. In the above embodiment, the coal 2 stored in the coal storage tank 1 is fed to the wet ball mill 4 with a predetermined coal feed amount by the metering coal feeder 3, and at the same time, water and dispersant are supplied to the water supply pipe 5 and the dispersant. Water is supplied from the supply pipe 8 to the wet ball mill 4 at a predetermined amount by the water supply flow rate control valve 7. Then, the coal 2 is atomized by wet pulverization by the operation of the wet ball mill 4, becomes a slurry 10, and is led to a vibrating sieve 11. At this time, the temperature of the slurry 10 increases due to the heat of crushing. After the coarse particles of coal contained in the slurry 10 are separated and removed, heat exchange is performed in the cooling chamber 12 by direct contact with the air flow from the inlet air pipe 13, and the slurry is cooled and at the same time moisture moves to the airflow side of the outlet air tube 26. This results in a humidity change in the air stream before and after the slurry contacts the air stream. Therefore, the humidity of the air flow in the inlet air pipe 13 and the outlet air pipe 26 is measured, and is input to the main controller 31 and processed, and the air flow rate and temperature are taken into consideration for the amount of humidity change. The amount of moisture change, in other words, the amount of moisture evaporation, is determined by calculation. Next, a signal 34 is output, which is set so that the water supply amount is corrected by the water evaporation amount of the slurry for the required water content of the slurry product, and the water supply flow rate is operated and controlled, and at the same time, the coal feed amount is operated. , control enables accurate slurry moisture control with high accuracy.

In this way, according to the above embodiment, when producing coal water slurry using a wet mill, the amounts of coal and water supplied are adjusted under ratio control in order to control the slurry moisture content, and the coal and water slurry is The amount of water supplied is corrected based on the amount of slurry moisture evaporated as the temperature rises due to the heat of grinding the slurry, and the amount of water supplied is corrected based on the detection of the humidity change in the air flow before and after the contact between the coal water slurry and the air flow in the cooling chamber.
The above correction can be performed reliably, and even when the coal-water slurry production process is influenced by complex fluctuation factors, accurate slurry moisture control can be performed with a high accuracy rate.

The embodiments of the present invention are not limited to the above embodiments, and various embodiments can be adopted.

〔Effect of the invention〕

As is clear from the above embodiments, the present invention is aimed at controlling the moisture content of the slurry in a coal-water slurry manufacturing method in which coal is slurried in a wet mill and the slurry whose temperature has risen due to the heat of grinding is cooled by an air flow. The amount of water evaporated in the slurry is calculated based on the detection of humidity changes in the air flow before and after contact with the air flow, and the amount of water supplied to the wet mill is reliably corrected and operated. This method has the remarkable effect of being able to accurately control slurry moisture with a high accuracy rate even when it is affected by complex fluctuation factors.

[Brief explanation of drawings]

FIG. 1 is a schematic flow sheet according to an embodiment of the present invention. 2...Coal, 4...Wet mill, 5...Water supply pipe, 7...
Water supply flow rate control valve, 12...Cooling chamber, 13...Inlet air pipe, 14, 27...Hygrometer, 20...Slurry, 26
...Outlet air pipe, 31...Main controller.

Claims (1)

[Claims] 1. A slurry moisture control method in a coal-water slurry manufacturing method in which coal is wet-pulverized with water and a dispersant in a wet mill to form a slurry, and the slurry, whose temperature has risen due to the heat of crushing, is cooled by air flow. The amount of moisture evaporated is calculated by detecting the humidity change in the air flow before and after contact with the air flow,
A method for controlling slurry moisture in a coal-water slurry manufacturing method, which comprises controlling slurry moisture by controlling the amount of water supplied to a wet mill.