What size of boiler or evaporator requires continuous blowdown or periodic blowdown?

The purpose of starting the drainage is to flush out the water sludge from the boiler drum, the lower header, and the bottom of the evaporator, thereby preventing blockages and scaling. The purpose of fast opening and fast closing is to increase the flow rate and improve the efficiency of draining slag, without affecting the liquid level. (The fixed-drain valves for small boilers and small evaporators are also known as quick-opening valves; a dedicated quick-opening valve is installed in series behind the stop valve to facilitate rapid opening and closing.) Operating at low flow rates for extended periods of time certainly does not yield good results. I’ve never checked the specifications. The smallest boiler I’ve seen was 2 tons in capacity (it’s difficult to find boilers that are even smaller); it was a saturated steam boiler operating at 0.6 Mpa, and it was equipped with a fixed-drain system (no continuous drainage – drainage took place at regular intervals during each shift) ； The evaporation rate of the jacket around the gas generator is also about 2 tons; continuous blowdown is performed. The fundamental purpose of continuous and periodic boiler drainage is to ensure the quality parameters of the boiler water. Indicators of feedwater, boiler water, and steam-water are prerequisites for ensuring the safe and stable operation of boilers. Low-pressure boilers must comply with GB/T 1576-2018, Water quality for industrial boilers.

The continuous or intermittent blowdown of boilers or evaporators needs to be determined based on the specific size and usage conditions. Generally, when the evaporator or boiler is of large scale, a continuous or periodic drainage system is required. Regarding the regulatory requirements for sequential and simultaneous discharge, different ** and regions may have varying standards; it is necessary to refer to the local environmental regulations and emission standards. For example, China’s GB13271-2014 standard for atmospheric pollutant emissions from boilers specifies the emission limits and requirements for such boilers. The reason for requiring large discharge volumes over a short period of time is to ensure complete combustion within the furnace and to prevent pollutant emissions from exceeding regulatory limits. By discharging a large volume of exhaust gas at once, it is possible to keep the concentration of pollutants in the exhaust gas low, thereby meeting environmental emission standards. If the flow rate is lower and the duration is longer, it will lead to an increase in the concentration of pollutants in the exhaust gases, failing to meet the emission standards. Therefore, during the design and operation phases, it is necessary to reasonably set the relevant parameters for sequential or fixed sequencing according to specific circumstances, so as to meet the corresponding environmental protection requirements. .

I'm referring to the continuous and periodic drainage of water from the pot