Daily Question (November 30)

A too rapid change in steam pressure can have many adverse effects on the unit, the main ones being: (1) deterioration of the water circulation: when steam pressure drops suddenly, water may vaporize in the downcomer tubes. When the steam pressure rises suddenly, the saturation temperature increases, which reduces the amount of vapor generated in the rising pipe and causes an instantaneous halt in the water circulation. The faster the rate of change in steam pressure, the greater the magnitude of that change, and this phenomenon becomes more pronounced. Tests have shown that for boilers operating at high pressures, the allowable rate of decline in steam pressure without causing disruption to the water circulation is no more than 0.25~0.30 MPa/min ； When the load is above medium level, the rate of increase in steam pressure is not more than 0.25 MPa/min, whereas at low loads, the rate of change in steam pressure is not more than 0.025 MPa/min. (2) False water levels are likely to occur: An increase or decrease in steam pressure causes the volume of the boiler water to contract or expand, which leads to a drop or rise in the water level in the drum; both situations represent false water levels. The faster the rate of change in steam pressure, the more pronounced the effect of false water level. When false water levels occur, improper adjustment or misoperation can easily lead to water shortage or overflow accidents.

Effects of rapid changes in steam pressure on the unit: (1) It deteriorates the water circulation: When steam pressure drops suddenly, water may vaporize in the downcomer. When the steam pressure rises suddenly, the saturation temperature increases, which reduces the amount of vapor generated in the rising pipe and causes an instantaneous halt in the water circulation. The faster the rate of change in steam pressure, the greater the magnitude of that change, and this phenomenon becomes more pronounced. Tests have shown that for boilers operating at high pressures, the allowable rate of decline in steam pressure that will not cause disruption to the water circulation is no more than 0.25–0.30 MPa/min ； When the load is above medium level, the rate of increase in steam pressure is not more than 0.25 MPa/min, whereas at low loads, the rate of change in steam pressure is not more than 0.025 MPa/min. (2) False water levels are likely to occur: An increase or decrease in steam pressure causes the volume of the boiler water to contract or expand, which leads to a drop or rise in the water level in the drum; both situations represent false water levels. The faster the rate of change in steam pressure, the more pronounced the effect of false water level. When false water levels occur, improper adjustment or misoperation can easily lead to water shortage or overflow accidents.

A too rapid change in steam pressure can have many adverse effects on the unit, the main ones being: (1) deterioration of the water circulation: when steam pressure drops suddenly, water may vaporize in the downcomer tubes. When the steam pressure rises suddenly, the saturation temperature increases, which reduces the amount of vapor generated in the rising pipe and causes an instantaneous halt in the water circulation. The faster the rate of change in steam pressure, the greater the magnitude of that change, and this phenomenon becomes more pronounced. Tests have shown that for boilers operating at high pressures, the allowable rate of decline in steam pressure without causing disruption to the water circulation is no more than 0.25~0.30 MPa/min ； When the load is above medium level, the rate of increase in steam pressure is not more than 0.25 MPa/min, whereas at low loads, the rate of change in steam pressure is not more than 0.025 MPa/min. (2) False water levels are likely to occur: An increase or decrease in steam pressure causes the volume of the boiler water to contract or expand, which leads to a drop or rise in the water level in the drum; both situations represent false water levels. The faster the rate of change in steam pressure, the more pronounced the effect of false water level. When false water levels occur, improper adjustment or misoperation can easily lead to water shortage or overflow accidents.

1 Swing in the opening degree of the steam inlet control valve. 2 Water level fluctuations are intensifying; manual release may be necessary. 3 Under coordinated operation, coal supply variations increase, air supply volume changes significantly, and negative pressure fluctuates greatly. 4 The oxygen level fluctuates greatly. The pressure fluctuation of the 5-axis seal is large. 6 The backlash increases. Adjust the unit operation so that the boiler follows, stabilize the coal and air supply to the boiler, and adjust the drum water level and furnace negative pressure in a timely manner.

A too rapid change in steam pressure can have many adverse effects on the unit, the main ones being: (1) deterioration of the water circulation: when steam pressure drops suddenly, water may vaporize in the downcomer tubes. When the steam pressure rises suddenly, the saturation temperature increases, which reduces the amount of vapor generated in the rising pipe and causes an instantaneous halt in the water circulation. The faster the rate of change in steam pressure, the greater the magnitude of that change, and this phenomenon becomes more pronounced. Tests have shown that for boilers operating at high pressures, the allowable rate of decline in steam pressure without causing disruption to the water circulation is no more than 0.25~0.30 MPa/min ； When the load is above medium level, the rate of increase in steam pressure is not more than 0.25 MPa/min, whereas at low loads, the rate of change in steam pressure is not more than 0.025 MPa/min. (2) False water levels are likely to occur: An increase or decrease in steam pressure causes the volume of the boiler water to contract or expand, which leads to a drop or rise in the water level in the drum; both situations represent false water levels. The faster the rate of change in steam pressure, the more pronounced the effect of false water level. When false water levels occur, improper adjustment or misoperation can easily lead to water shortage or overflow accidents.

A too rapid change in steam pressure can have many adverse effects on the unit. The main ones are: 1. It deteriorates the water circulation; when steam pressure drops suddenly, water may vaporize in the downcomer. When the steam pressure rises suddenly, the saturation temperature increases, which reduces the amount of vapor generated in the rising pipe and causes an instantaneous halt in the water circulation. The faster the rate of change in steam pressure, the greater the magnitude of that change, and this phenomenon becomes more pronounced. Tests have shown that for boilers operating at high pressures, the allowable rate of drop in steam pressure without causing disruption to the water circulation is not more than 0.25–0.30 MPa/min ； When the load is above medium level, the rate of increase in steam pressure is not more than 0.05 MPa/min, whereas at low loads, the rate of change in steam pressure is not more than 0.025 MPa/min. 2. False water levels are likely to occur. An increase or decrease in steam pressure can cause the volume of the water in the boiler to contract or expand, resulting in a drop or rise in the water level in the drum; both situations represent false water levels. The faster the rate of change in steam pressure, the more pronounced the effect of false water level. When false water levels occur, improper adjustment or misoperation can easily lead to water shortage or overflow accidents.

What are the effects of too rapid a change in steam pressure? Answer: A too rapid change in steam pressure can have many adverse effects on the unit. The main ones are: (1) It deteriorates the water circulation: when steam pressure drops suddenly, water may vaporize in the downcomer. When the steam pressure rises suddenly, the saturation temperature increases, which reduces the amount of vapor generated in the rising pipe and causes an instantaneous halt in the water circulation. The faster the rate of change in steam pressure, the greater the magnitude of that change, and this phenomenon becomes more pronounced. Tests have shown that for boilers operating at high pressures, the allowable rate of decline in steam pressure without causing disruption to the water circulation is no more than 0.25~0.30 MPa/min ； When the load is above medium level, the rate of increase in steam pressure is not more than 0.25 MPa/min, whereas at low loads, the rate of change in steam pressure is not more than 0.025 MPa/min. (2) False water levels are likely to occur: An increase or decrease in steam pressure causes the volume of the boiler water to contract or expand, which leads to a drop or rise in the water level in the drum; both situations represent false water levels. The faster the rate of change in steam pressure, the more pronounced the effect of false water level. When false water levels occur, improper adjustment or misoperation can easily lead to water shortage or overflow accidents.

A too rapid change in steam pressure can have many adverse effects on the unit, the main ones being: (1) deterioration of the water circulation: when steam pressure drops suddenly, water may vaporize in the downcomer tubes. When the steam pressure rises suddenly, the saturation temperature increases, which reduces the amount of vapor generated in the rising pipe and causes an instantaneous halt in the water circulation. The faster the rate of change in steam pressure, the greater the magnitude of that change, and this phenomenon becomes more pronounced. Tests have shown that for boilers operating at high pressures, the allowable rate of decline in steam pressure without causing disruption to the water circulation is no more than 0.25~0.30 MPa/min ； When the load is above medium level, the rate of increase in steam pressure is not more than 0.25 MPa/min, whereas at low loads, the rate of change in steam pressure is not more than 0.025 MPa/min. (2) False water levels are likely to occur: An increase or decrease in steam pressure causes the volume of the boiler water to contract or expand, which leads to a drop or rise in the water level in the drum; both situations represent false water levels. The faster the rate of change in steam pressure, the more pronounced the effect of false water level. When false water levels occur, improper adjustment or misoperation can easily lead to water shortage or overflow accidents.

1# Stand in the east 1. The opening of the steam inlet control valve fluctuates. 2. Water level fluctuations are intensifying; manual intervention may be necessary. 3. Under coordinated operation, coal supply variations increase, air supply volume changes significantly, and negative pressure fluctuates greatly. 4. Except for the large fluctuations in oxygen level. 5. The shaft seal pressure fluctuates greatly. 6. The differential expansion increases. Adjust the unit coordination so that the boiler follows, stabilizing the coal and air supply to the boiler. Adjust the drum water level and furnace negative pressure in a timely manner.

(1) Worsening of water circulation: When the steam pressure drops suddenly, water may vaporize in the downcomer. When the steam pressure rises suddenly, the increase in saturation temperature leads to a decrease in the amount of steam generated in the rising pipe, which causes an instantaneous halt in the water circulation. (2) False water levels can occur: An increase or decrease in steam pressure results in a contraction or expansion of the volume of water in the boiler, causing the water level in the drum to drop or rise; both situations represent false water levels. The faster the rate of change in steam pressure, the more pronounced the effect of false water level. When false water levels occur, improper adjustment or misoperation can easily lead to water shortage or overflow accidents.