A multi-cone, multi-stage spray nozzle includes a nozzle body and outer and inner valve stems. The nozzle body defines an outer valve seat disposed at its distal end. The outer valve stem is slidably disposed in the nozzle body. The inner valve stem is slidably disposed in the outer valve stem. The inner valve stem occupies an open position and the outer valve stem occupies a closed position upon the application of a first pressure on the distal ends of the inner and outer valve stems. And, the inner and outer valve stems both occupy open positions upon the application of a second pressure that is greater than the first pressure on the distal ends of the inner and outer valve stems.

An integrated pressure and temperature reducing device, comprising a secondary steam pipe and a temperature and pressure reducing mechanism arranged within the secondary steam pipe; the temperature and pressure reducing mechanism comprises an upper valve cover and a spool; the spool is provided with a plurality of pressure reducing holes, and a valve stem is inserted at one end of the spool; an end of the valve stem which is close to the spool is provided with a water supply passage, an outer peripheral surface of the valve stem is provided with a plurality of water inlet holes which are in communication with the water supply passage; the other end of the spool is inserted with a temperature reducing water pipe, and an end of the temperature reducing water pipe which is close to the valve stem is provided with a water outlet passage.

An integrated pressure and temperature reducing device, comprising a secondary steam pipe and a temperature and pressure reducing mechanism arranged within the secondary steam pipe; the temperature and pressure reducing mechanism comprises an upper valve cover and a spool; the spool is provided with a plurality of pressure reducing holes, and a valve stem is inserted at one end of the spool; an end of the valve stem which is close to the spool is provided with a water supply passage, an outer peripheral surface of the valve stem is provided with a plurality of water inlet holes which are in communication with the water supply passage; the other end of the spool is inserted with a temperature reducing water pipe, and an end of the temperature reducing water pipe which is close to the valve stem is provided with a water outlet passage.

A method of operating a combined heat and power plant includes, when there is insufficient heat removal from a hot flue gas downstream from a hot flue gas generator but upstream of a steam evaporator, as a result of insufficient mass flow of imported steam to a steam superheater, to prevent the hot flue gas temperature downstream of the steam superheater from rising to or above a predetermined limit, quenching steam inside the steam superheater or quenching steam being fed to the steam superheater by injecting boiler feed water or condensate into the steam to produce steam in the steam superheater. The quenching increases the removal of heat from the hot flue gas and reduces the hot flue gas temperature downstream of the steam superheater to ensure that the hot flue gas temperature downstream of the steam superheater does not rise to or above the predetermined limit.

A method of operating a combined heat and power plant includes, when there is insufficient heat removal from a hot flue gas downstream from a hot flue gas generator but upstream of a steam evaporator, as a result of insufficient mass flow of imported steam to a steam superheater, to prevent the hot flue gas temperature downstream of the steam superheater from rising to or above a predetermined limit, quenching steam inside the steam superheater or quenching steam being fed to the steam superheater by injecting boiler feed water or condensate into the steam to produce steam in the steam superheater. The quenching increases the removal of heat from the hot flue gas and reduces the hot flue gas temperature downstream of the steam superheater to ensure that the hot flue gas temperature downstream of the steam superheater does not rise to or above the predetermined limit.

A spray nozzle assembly for a steam desuperheating or attemperator device. In one embodiment, the spray nozzle sub-assembly of the spray nozzle assembly comprises a fixed nozzle element which is integrated into a spring-loaded nozzle element, and is specifically adapted to improve water droplet fractionation at higher flow rates while further providing an effectively higher spray area through the formation of two water cones (rather than a single water cone), such water cones being sprayed into a flow of superheated steam in order to reduce the temperature of the steam. In another embodiment, the spray nozzle sub-assembly of the spray nozzle assembly comprises a nested pair of spring-loaded primary and secondary nozzle elements which are also adapted to provide an effectively higher spray area through the formation of two water cones.

A device for closed-loop control of a plurality of state variables of a steam generator of a thermal power plant is provided. In order to achieve stable and exact closed-loop control of the plurality of state variables, a multi-variable control/controller controls the plurality of state variables and uses a linear quadratic controller for this multi-variable control/controller.

A method of operating a combined heat and power plant (10) (CHP plant) includes generating hot flue gas and cooling the hot flue gas in a sequence of cooling steps to recover heat and to generate steam in a heat recovery steam generator (16) (HRSG). The HRSG (16) includes an LP steam evaporator (36) designed to generate steam at least over a pressure range of from 2 bar(g) to 18 bar(g) so that either LP steam or MP steam can selectively be generated by the LP steam generator (36), thereby to cool the hot flue gas, and an MP steam superheater (24) upstream of the LP steam evaporator (36) to superheat MP steam in heat exchange with the hot flue gas thereby to cool the hot flue gas. The method further includes, when no or insufficient MP steam is being imported to the MP steam superheater (24) to ensure safe operation of the MP steam superheater, and/or when a demand exists for exporting MP steam which cannot be satisfied by imported MP steam superheated in the MP steam superheater (24), and/or when a demand exists for MP steam in the CHP plant which cannot be satisfied by imported MP steam, operating the LP steam evaporator (36) at an operating pressure in the range of between 8 bar(g) and 18 bar(g) to generate MP steam to wet the MP steam superheater (24) and/or to satisfy at least to some extent said demand for MP steam, and thereafter, when sufficient MP steam is being imported to the MP steam superheater (24) from external of the CHP plant (10) to ensure safe operation of the MP steam superheater (24), and/or when any demand for exported MP steam is satisfied by imported MP steam which is superheated in the MP steam superheater (24) and then exported, and/or when there is no more demand for exporting of MP steam, and/or when the demand for MP steam in the CHP plant (10) is being satisfied at least to some extent by imported MP steam, reducing the operating pressure of the LP steam evaporator (36) to a pressure in the range of between 2 bar(g) and 8 bar(g) thereby to generate LP steam.

A method of operating a combined heat and power plant (10) (CHP plant) includes generating hot flue gas and cooling the hot flue gas in a sequence of cooling steps to recover heat and to generate steam in a heat recovery steam generator (16) (HRSG). The HRSG (16) includes an LP steam evaporator (36) designed to generate steam at least over a pressure range of from 2 bar(g) to 18 bar(g) so that either LP steam or MP steam can selectively be generated by the LP steam generator (36), thereby to cool the hot flue gas, and an MP steam superheater (24) upstream of the LP steam evaporator (36) to superheat MP steam in heat exchange with the hot flue gas thereby to cool the hot flue gas. The method further includes, when no or insufficient MP steam is being imported to the MP steam superheater (24) to ensure safe operation of the MP steam superheater, and/or when a demand exists for exporting MP steam which cannot be satisfied by imported MP steam superheated in the MP steam superheater (24), and/or when a demand exists for MP steam in the CHP plant which cannot be satisfied by imported MP steam, operating the LP steam evaporator (36) at an operating pressure in the range of between 8 bar(g) and 18 bar(g) to generate MP steam to wet the MP steam superheater (24) and/or to satisfy at least to some extent said demand for MP steam, and thereafter, when sufficient MP steam is being imported to the MP steam superheater (24) from external of the CHP plant (10) to ensure safe operation of the MP steam superheater (24), and/or when any demand for exported MP steam is satisfied by imported MP steam which is superheated in the MP steam superheater (24) and then exported, and/or when there is no more demand for exporting of MP steam, and/or when the demand for MP steam in the CHP plant (10) is being satisfied at least to some extent by imported MP steam, reducing the operating pressure of the LP steam evaporator (36) to a pressure in the range of between 2 bar(g) and 8 bar(g) thereby to generate LP steam.

An automated control loop for dynamically adjusting a temperature of wet steam is provided. This leads to increased heat transfer and decreased fouling in a reboiler of a distillation column used for distilling a petrochemical. The control loop includes controlling the combining of condensed water with dry steam to produce the wet steam. The produced wet steam is input to the reboiler in order to transfer heat to the petrochemical while being converted to the condensed water. The control loop further includes monitoring a pressure of the produced wet steam, and setting a target temperature for the produced wet steam based on the monitored pressure. In addition, the control loop includes monitoring the temperature of the produced wet steam, and adjusting a proportion of the condensed water in the produced wet steam in response to the monitored temperature deviating from the set target temperature by at least a threshold value.