Design Research On The Selection Schemes Of Regeneration Heat Source Of Active Coke For Coal-Fired Flue Gas Purification

Flue gas purification technology using active coke is a multi-pollutant integrated removal technology,which has a broad application prospect in coal-fired power plants.The regeneration of active coke is one of the key steps.Thermal regeneration consumes a lot of energy,but it is worth discussing to adopt a lower grade heat source in coal-fired power plants,namely,flue gas and low-pressure steam.Taking a 660 MW ultra-supercritical unit as an example,this paper puts forward six plans,which extract the flue gas from the front of the secondary economizer,the low-temperature superheater of the rear flue and the low-temperature reheater of the front flue,to return to the air preheater and the cold ash hopper,among which the flue gas extracted from the front of the secondary economizer needs to be supplemented by No.4 extraction steam and returned to the deaerator.According to the flue gas extraction point,three kinds of heating sections of regeneration tower were designed,the flue gas and steam temperature were checked at the outlet of the regeneration tower under high,medium and low load.And the overall thermal calculation of each scheme was carried out under each load,the regenerative system calculation was also carried out to obtain the influence of each scheme on the main parameters of the unit under each load in schemes 1 and 4,then the economic and applicability analysis of each scheme was carried out.The results show that:for plans 1 and 4,the flue gas heating section is divided into three sections of heat exchanger in series,the heat exchange area of flue gas section is26633.22 m²,and the height of flue gas section is 13.91 m;steam heating is applied additionally under low load,the heat exchange area of steam section is 5600.64 m²,and the height of steam section is 2.93 m.For plans 2 and 5,the flue gas heating section is divided into two sections of heat exchanger in series,the heat exchange area of the flue gas section is 14607.03 m²,and the height of the flue gas section is 7.55 m.For plans 3and 6,the flue gas heating section is divided into two sections of heat exchanger in series,with heat exchange area of 13566.25m² and height of 7.21m.For each scheme Under each load,the flue gas and steam have certain influence on the parameters of the unit,but the main and reheat steam parameters can be kept stable through adjustment,and other parameters are within the normal range,which has no influence on the safe operation of the unit,and can stably provide heat for the active coke.Under BMCR load,coal consumption of power supply increased by 3.34g·（k W·h）^-1,3.64g·（k W·h）^-1,3.69g·（k W·h）^-1,4.16g·（k W·h）^-1,4.21g·（k W·h）^-1 and 4.21g·（k W·h）^-1respectively.Under 75%THA load,the coal consumption of power supply increases respectively by 4.89 g·（k W·h）^-1,5.16 g·（k W·h）^-1,5.35 g·（k W·h）^-1,5.83 g·（k W·h）^-1,5.78g·（k W·h）^-1 and 5.67 g·（k W·h）^-1.Under 50%THA load,the coal consumption of power supply increases by 10.34 g·（k W·h）^-1,8.11 g·（k W·h）^-1,8.19 g·（k W·h）^-1,10.21 g·（k W·h）^-1,8.27 g·（k W·h）^-1 and 8.33 g·（k W·h）^-1 respectively.The heat source plan shall be determined according to the actual operation of the unit:if the unit is in high load operation state for a long time,scheme 1 can be selected as the heat source;if the unit also has low reheat steam temperature or high NOx content in flue gas,or burning lignite with high moisture content,scheme 4 can be used as the desorption heat source of active coke.If the unit is in the medium load state for a long time,option 1 can be selected as regeneration heat source;at the same time,if the unit has the above characteristics,option 6 can be used as the heat source while the impact on the wear of the economizer should be considered.If the unit is in low load operation state for a long time,option 2 can be selected as the analytical heat source;if the unit has the above characteristics meanwhile,option 5 can be used as the desorption heat source while the combustion stability of the furnace shall be considered and the steam at the outlet of the separator shall be ensured to be overheated.