DD289214A5 - HYBRID PROCESS FOR INTENSIVING WET SMOKE GAS CLEANING WITH INTEGRATED WATER RECOVERY FOR BROWN COAL-FIRED COMBUSTION ENGINES - Google Patents

Abstract

Hybrid method for intensifying the wet flue gas cleaning with integrated heat recovery for lignite fired incineration plants is an invention that allows high Schadstoffabscheidegrade even at high sulfur dioxide levels and high heat recovery by using the flue gas enthalpy to below the adiabatic limit temperature are possible. The erfindungsmaeszigen method a simplification of Betriebsfuehrung is achieved {Schadstoffabscheidung; heat recovery; adiabatic limit temperature; heat transfer; lignite-fired incinerators}

Description

Heat flow is subsequently transferred by means of a surface heat transfer to a cooling medium. In this context, the washing suspension mass flow is fully adapted to the desired degree of pollutant removal and at the same time a recovery of the flue gas enthalpy to below the adiabatic limit temperature realized. The extracted from the flue gas heat flow can be adjusted by adjusting the cooling medium flow and its inlet temperature to the needs of the customer. The washing suspension is used both for separating the pollutants and for heat transport. The low heating of the washing suspension flow means with the subsequently inevitably also low cooling of the suspension in the downstream heat transfer to the cooling medium, that in this heat transfer almost the maximum possible average temperature difference to the cooling medium effectively and thus Minimiurung the heating surface is made possible. The power supply is freely selectable and has almost no influence on the transferred heat flow. The state change of the flue gas associated with this method includes, with the specified choice of falling below the adiabatic limit temperature, a wastewater-free or low-waste water operation.

embodiment The invention will be explained in more detail below with reference to two embodiments. 1 shows the state changes of the flue gas with boiler outlet parameters when using the described Process. The flue gas occurs at a temperature of t (1) = 200 ° C, an absolute humidity of χ (1) = 15Gg / kg and thus one Enthalpy of h (1) = 645 kJ / kg. Thereafter, the flue gas through a trickled in countercurrent wash suspension

first almost isenthalp, according to the temperature of the suspension, to the adiabatic limit temperature of t (2) = 67 ⁰ C moistened with χ (2) - 220g / kg and then the further cooling to t (3) = 62.5 ⁰ C. with χ (3) = 164g / kg. Daboi heats the suspension mass flow of 113.8kg / s by 1K. The heated wash suspension is below the

Contact internals recuperative in a heat exchanger, which is completely surrounded by the suspension, through Use water cooled. On the basis of a 6.5t / h steam generator with an average flue gas mass flow of 3kg dry Flue gas per second results in the heat exchanger at an area of 38.7 m ² an associated Heat transfer coefficient of 1214W / m'K. This corresponds to a useful heat flow of 484 kW, which is due to the large

average temperature difference of 10.3 K is justified. This will give a customer a thermal output of 11.3% of

Steam generator power provided. The deposition process is wastewater-free. Figure 2 shows the state changes for precooled flue gases using the method described. The flue gas occurs at a temperature of t (1) = 149 ° C, an absolute humidity of χ (1) = 155g / kg and thus one Enthalpy of h (1) = 579 kJ / kg. Thereafter, the flue gas is a scrubbing suspension trickled in countercurrent first

close to isenthalp according to the suspension temperature to the adiabatic limit temperature of t (2) = 65 ⁰ C moistened with χ (2) = 190g / kg, followed by further cooling to t (3) = 60 ° Cmitx (3) = 15Og / kg. The suspension mass flow of 35.4 kg / s is heated by 2.6 K. The heated washing suspension is cooled recuperative in a cross-countercurrent heat exchanger by hot tap water below the contact inserts.

Based on a 6.5 t / h steam generator with an average flue gas mass flow of 3 kg dry Flue gas per second results in countercurrent at an area of 38.7 m ^2, an associated heat transfer coefficient

of 931 W / m ² K. This corresponds to a useful heat flow of 388 kW, which is due to the large mean temperature difference of 10.8 K. This provides a customer with a heat output of 9.1% of the steam generator capacity.

The resulting condensation water from the flue gas is removed with the solid waste product.

Claims (3)

Hybrid method for intensifying the wet flue gas cleaning with integrated heat recovery for lignite fired incinerators, in which the flue gas is contacted by a wash suspension in countercurrent and the wash suspension absorbs the pollutants and subsequently emits heat to a cooling medium recuperative, characterized in that the washing suspension mass flow according to the desired pollutant binding so is chosen that he experiences a heating of at most 3 K and while the flue gas is cooled to a maximum of 6 K below the adiabatic limit temperature, said absorbed by the washing suspension heat flow is adjusted by means of a heat exchanger by the appropriate setting Her coolant parameters to the consumer needs. For this 2 pages drawings Field of application of the invention The hybrid process for intensifying the wet flue gas cleaning with integrated heat recovery is for all brown coal fired incinerators! anwenabar. Characteristic of the known state of the art The high pollutant load of the environment requires the establishment of emission control systems that make a portion of the smoke gas energy usable at a high degree of separation of pollutants, especially SO] and low system costs and that with a relatively high temperature without affecting the operation of the incinerator negative. Numerous methods and arrangements are known from the literature, but they do not fully meet the specific demands placed on the effective pollutant removal from flue-gas lignite-fired incinerators. Typical representatives of wet processes used in particular are described in DD269756, DD 215475, and DE 3737500. Heat recovery does not occur in the vast majority of processes. In DD215475 a method with heat recovery is shown. The disadvantage here is that pollutant separation and heat recovery are coupled in opposite directions. The essence of this method is that heat of the highest possible energy level is to be recovered from the flue gas, using counter or cross-countercurrent heat transfer. This means at the same time intended cooling of the flue gases up to 4O ⁰ C and the highest possible warming of the pollutants receiving scrubbing that the washing suspension mass flow is limited according to the heat capacities. In contrast, a high degree of pollutant incorporation from the flue gases of lignite-fired plants requires significantly higher wash suspension flows. If after DD215475 a flue gas cooling to 4O ⁰ C and a washing suspension heating up in the proximity of the adiabatic temperature limit, a ratio of washing suspension to wet flue gas from results on the recognition of the relevant heat flow is less than 4 kg / kg. Our own tests on a wet flue gas desulphurisation plant showed SOy separation rates below 70% for brown coal of medium sulfur content. This corresponds to experiences of international literature. This regime of heat recovery limits the achievable degree of separation in a wide range of practical applications. It also requires a high regulatory effort. Furthermore, the method works with intentional flue gas cooling up to 40 ° C due to condensate accumulation not waste water, so that the required wastewater treatment and discharge requires additional expenses. Object of the invention The aim of the invention is to make a method of pollutant reduction and heat recovery from the flue gases lignite fired plants so that high Schadstoffabscheidegrade are possible even at high Schwefeldioxidgehalten and high heat recovery levels by using the enthalpy of the flue gases to below the adiabatic limit temperature. Explanation of the essence of the invention The invention has for its object to provide a hybrid method for intensifying the wet flue gas cleaning with integrated heat recovery for lignite fired incinerators, which combines a high separation efficiency of pollutants and variable waste heat utilization to below the adiabatic Grenztomperatur and sewage-free or -arm works. According to the invention, the object is achieved in that flue gas in a known manner in a? Contact apparatus in countercurrent by a sufficiently large washing liquid mass flow, is released to the desired extent of pollutants, wherein the thermo-technical part of the process is designed so that the washing suspension flow by a maximum 3 K heats up and the flue gas cools by a maximum of 6 K below the adiabatic limit temperature and this transferred