Steam condensate heat pump system based on tail gas flow rate detection

Abstract

The invention belongs to the technical field of paper making, in particular to a steam condensate heat pump system based on tail gas flow rate detection used for a drying part of a paper machine. The system comprises a primary drying cylinder group and a secondary drying cylinder group, wherein siphon devices are arranged in drying cylinders; the gas inlet and the gas outlet of the primary cylinder group are respectively connected with a gas inlet main pipe and a water drainage pipe of the system; a gas-liquid separator is arranged at the output end of the water drainage pipe; and the output end of the gas-liquid separator is connected with a condensate pump. The system is characterized by also comprising a tail gas flow rate control module used for recycling tail gas, and a gas inlet pressure control module used for controlling the pressure of the primary drying cylinder group. The drying cylinder group of the heat pump system provided by the invention has a wide operating pressure range, high drying capacity, high drainage reliability, low gas consumption of paper per ton, simple system operation, long service life and high work efficiency.

Description

technical field [0001] The invention belongs to the technical field of papermaking, and in particular relates to a steam condensed water heat pump system based on tail gas flow detection used in a drying section of a paper machine. Background technique [0002] In the papermaking process, the most common way to dry paper is to feed fresh steam into the rotary dryer to heat and dry the paper on the forming net in the dryer. The fresh steam is finally converted into condensed water and the tail gas composed of through steam and non-condensable gas is discharged out of the dryer. During the continuous drying process of paper sheets, a part of the fresh steam passed into the drying cylinder conducts heat exchange with the inner wall of the drying cylinder, and the heat released is converted into condensed water. Part of the heat is not exchanged but discharged out of the dryer along with the condensed water, which is called through steam in the industry, and a small part of non...

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Problems solved by technology

[0013] 1. In order to ensure unobstructed drainage in the pressure difference control system, the set value of the pressure difference at the inlet and outlet of the dryer group is often much larger than the actual drainage demand, and the pressure difference between the sections must also be large enough. The consequence of this setting is that the exhaust gas Too much, even if the heat pump is turned on to 100%, it still cannot compress all the exhaust gas

In addition, because the low temperature section works at a lower pressure, the low temperature section cannot receive too much exhaust gas, and the medium and high temperature sections can only open the vent valve to discharge the exhaust gas to the surface condenser, which wastes a lot of steam and waste lots of cooling water

At present, many paper mills are in such a state of serious waste

[0014] 2. During the threading process, the temperature of the drying cylinder should not be too high, so the steam pressure entering the drying cylinder must be low

In the cascade differential pressure control system, the pressure differences between the sections restrict each other. To adjust the operating pressure of any section, the entire drying section must also be adjusted together. Otherwise, the system will have difficulty in drainage, which brings great difficulties to the on-site operation. difficulty

[0016] 4. The cascade differential pressure control system cannot allow the operator to understand the current operating status of the entire steam system well, and can only set the drain pressure differential at a set value that he considers "safe". The problem of smoothness cannot be known in time. Only when the QCS (Quality Control System) before the paper curls gives a warning of unqualified dryness, it is known that there is a problem, but it is still not clear which specific dryers are out. problem

This is obviously unscientific and wasteful

[0017] 5. The cascade differential pressure control system often has phenomena such as accumulation of water in the drying cylinder and excessive flow of exhaust gas, which will also cause impact on the paper machine equipment. For example, the siphon in the drying cylinder is often damaged by the impact of accumulated condensed water. damage, or the suction nozzle is worn due to the excessive flow of exhaust gas; the accumulation of water in the drying cylinder causes the bearing wear of the drying cylinder to increase and the transmission load is too large, and the transmission load is too large to cause abnormal current

Due to the complexity and inconvenience of the operation of the cascade differential pressure control system, it will consume a lot of production time, resulting in low production efficiency

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