JPS6156270B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the control of a high-temperature, high-pressure coal gasifier that processes ash in a molten state, and in particular to the control of a high-temperature, high-pressure coal gasifier that processes ash in a molten state. The present invention relates to a method and apparatus for monitoring and controlling the supply amount of an oxidizing agent (oxygen or air) necessary for gasification so as to maintain the same.

When coal is gasified to produce fuel gas or synthesis raw material gas, gasifiers are increasingly being operated at high temperatures and pressures in order to improve gasification efficiency and increase throughput.

However, when the temperature inside the gasifier is raised to 1,100°C or higher, the ash begins to melt and exhibits phenomena such as clinker formation or melting and solidification, leading to problems such as blockage in the furnace. For this reason, spouted bed and fused bed type gasifiers are used, in which the temperature inside the furnace is raised to a point where the ash is melted, and the ash is allowed to flow down from the bottom of the furnace as molten slag, which is then rapidly cooled and crushed to be taken out of the system. In such a gasifier, the lower oxidation reaction zone of the gasifier reaches a high temperature of 1,200 to 2,000°C to melt the ash, and the refractory material is eroded, making it impossible to withstand long-term operation.

For this reason, a self-coating method has been adopted in which the outside of the refractory material, that is, the gasifier shell, is cooled as a water-cooled wall, and the inside is covered with the molten slag itself to shield the heat and protect the refractory material. Since the outside of the refractory material is cooled, there is a temperature gradient with the inside of the furnace, and the slag is solidified at the contact surface between the refractory material surface and the slag, and the hot slag surface flows and flows down from the central slag tap. By maintaining this condition, the life of the refractory material will be extended. For this method to be successful, it is necessary that the molten slag forms a layer of adequate thickness to protect the refractory material.

Conventional slug tap coal gasifiers employ a control system that maintains a constant temperature in the furnace by detecting the temperature inside the furnace and controlling the amount of oxidizing agent supplied necessary for the reaction. According to this method, control is performed assuming that the quality of the coal is constant and the melting temperature of the ash is also constant.

However, the quality of coal is unstable and variable, and the ash content and melting temperature are usually not constant. It is also necessary to gasify various types of coal in the same gasifier, making it impossible to control the temperature within the furnace at the same level. If the temperature is not set to match the properties of the ash in the supplied coal, there is a risk that the molten slag layer will become thinner or thicker than necessary. In extreme cases, the slag layer may disappear and the refractory material erodes, or it may become too thick and block the slag tap.

The present invention prevents the above-mentioned dangers and supplies an oxidizing agent to maintain the molten slag layer at an appropriate thickness regardless of variations in coal type, quality variations, ash content, melting temperature, etc. The purpose is to operate a coal gasifier stably by controlling the amount of coal.

The oxidant supply rate control device according to the present invention is characterized by a mechanism for measuring and detecting the slug tap opening area or opening diameter using a slug tap hole detector installed in the slag cooling water tank (on the side wall or central water surface), and the detection mechanism. The method is based on a system that controls the amount of oxidizing agent supplied in reverse operation depending on the amount of change in the opening of the slug tap.

An embodiment of the present invention will be described below with reference to the drawings.

1 is a gasifier, 2 is a burner, 3 is a molten slag layer, 4 is a coal supply pipe, 5 is an oxidizer supply pipe, 6 is a slag tap, 7 is a slag cooling water tank, 8 and 9 are slag tap detectors, 10 is a conversion vessel, 11
12 is an oxidizer control valve, and 12 is a level detector 13 at the outlet of the gasifier.

In high-temperature gasifiers, coal is generally injected tangentially in a swirling manner within the gasifier using multiple burners, usually four or more, but coal is supplied by pneumatic transport such as circulating gas or steam. Alternatively, it may be injected into the gasifier 1 through the burner 2 by fluid transport using a water slurry (in this case, water may be evaporated before being injected into the furnace and airflow transport using steam may be used). Ru.

The burner 2 is directed towards a molten slag layer 3 (which may form a slag bath at the bottom of the furnace);
It is combined with a separately supplied oxidizing agent (oxygen or air) 5 to cause partial oxidation, water gasification, and other reactions to be gasified. The crude gas produced by the reaction flows out from the gasifier outlet 13. The ash in the coal melts due to the high temperature, flows on the slag surface, and flows down into the slag cooling water tank 7 through the slag tap 6 which opens at the center of the bottom of the gasifier.

When the molten slag flows down from the slug tap 6, when the amount of oxidizing agent is relatively small and the slag temperature is relatively low, the flow of the slag becomes poor and the opening of the slag tap 6 becomes smaller due to the slag sticking. When the amount of oxidizing agent is relatively large and the slug temperature is relatively high, the stuck slag also begins to flow out, and the opening of the slug tap 6 becomes larger. When the molten slag flows down and falls into the slag cooling water tank 7, the slag is crushed and becomes fine particles due to the temperature difference. This slug tap 6
The size of the opening is detected by the detector 8 (or 9, a detector with a converter), and the converter 10 issues a signal to control the oxidizer control valve 11 to change the amount of oxidant supplied. By this method, the slug tap 6
The size of the opening is controlled to a predetermined size.

Inert gas at the detection end of detector 8 or 9
Protect the detection lens from falling objects and water droplets by flowing N ₂ or CO ₂ or steam. The water level in the slag cooling water tank is kept constant by a level detector 12.

In the high-temperature gasifier that forms molten slag, the temperature inside the furnace is controlled so that the temperature is suitable for the coal ash to always melt and flow, but changes in the furnace load, changes in coal type, and differences in the ash melting temperature etc., the optimum temperature is not necessarily constant. In addition, there is currently a problem that the lifespan of temperature detectors at high temperatures is short.
In the partial oxidation reaction, it is necessary to maintain the ratio of the oxidizing agent and the amount of coal supplied within a range that does not cause the reaction temperature to become higher than necessary. It is necessary to maintain optimal fluidity of the molten slag.

For example, when gasifying A coal whose ash flow temperature is 1230℃, a photoelectric detector is used to detect the area of the slug tap and determine the amount of oxygen supplied.
0.474m ³ /Kg - operated as coal.

Next, when B coal with an ash flow temperature of 1360°C was used, the output of the detector decreased and the opening area of the slug tap became narrower, so the amount of oxygen supplied was reduced.
By increasing the coal to 0.562 m ³ /Kg-coal, the opening area of the slag tap showed a predetermined value, and the flow condition of the slag was maintained appropriately.

According to the present invention, the gasification reaction can be stably continued by directly monitoring and detecting the flow state of the slag and controlling the supply of the oxidizing agent.
The operational reliability of the coal gasifier can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an apparatus showing an embodiment of the present invention. 1; Gasifier, 2; Burner, 3; Molten slag layer, 4; Coal supply pipe, 5; Oxidizer supply pipe, 6;
Slug tap, 7; Slug cooling water tank, 8; Slug tap detector, 9; Slug tap detector (with converter), 10; Converter, 11; Oxidizer control valve, 12; Level detector, 13; Gasifier outlet,
14; Detector support; 15; Slug slurry.

Claims (1)

[Claims] 1. In a high-temperature coal gasification method in which coal is gasified by operating under high pressure and keeping the ash in a molten slag state, and this molten slag is rapidly cooled into a slurry and taken out of the gasifier system, the desired melting process is achieved. A method for controlling a coal gasifier, comprising controlling the amount of oxidizing agent supplied so as to form a slag layer in the gasifier. 2. In a coal gasifier in which a slag cooling water tank is installed through a slag flow hole in a gasifier equipped with a coal supply pipe and an oxidizer supply pipe, a slag tap detector is installed in the slag cooling water tank to determine the slug tap opening area. 1. A control device for a coal gasifier, comprising a circuit that inputs detected values into a computer to control the amount of oxidizer supplied to a desired level.