DD282749A5 - PROCESS FOR DETERMINING THE POLLUTION DEGRADATION OF TUBE BELT WELDING TRANSMITTERS - Google Patents

Abstract

The method according to the invention for determining the degree of soiling in tube-type heat exchangers makes it possible to assess the degree of soiling by simply measuring the temperature conditions in the unpolluted state and at the corresponding measuring times when the mass flows of the media are determined. shell and tube heat exchanger; Pollution degree; heat transfer}

Description

embodiment

The invention will be explained in more detail below using an exemplary embodiment. For heat recovery from flue gases brown coal fired combustion systems, a shell and tube heat exchanger is used, in which flows in the pipes and water around the pipes flue gas. The steam generator has a design capacity of 6.5t / h steam, with the parameters of the feedwater and steam at least during the measurements being the design values. The measurement of the media inlet and outlet temperatures at the heat exchanger by means of appropriate thermocouples. Before each measurement, the mass flows are set and driven constant for about 30 minutes. At the heat exchanger a water mass flow of 10m ³ / h and at the steam generator a steam capacity of 6t / h is set at 7% oxygen content in the flue gas at the boiler end. The first measurement of the inlet and outlet temperatures takes place after the first startup of the heat exchanger. All further measurements are made at fixed intervals. The following table shows two measurements. After calculation of the mean logarithmic temperature difference and the determination of the enthalpy values, preferably of the water, the degrees of contamination result.

I date

63 ⁰ C 78 ° C

209 ⁰ C 148 ⁰ C 0.34

commissioning Zeitpi water temperatures entry 58 ⁰ C 61 ⁰ C exit 89 ° C 82 ⁰ C Flue gas temperatures entry 205 ° C 204 ° C exit 102 ⁰ C. 135 ⁰ C pollution degree 1 0.52

Claims (2)

-1- 282 749 Invention claim: 1. A method for determining the degree of contamination in Rohrbündelwärmeübertragern, as the ratio of the heat transfer coefficients of the soiled and unpolluted condition, characterized in that the inlet and outlet temperatures of both media in the unpolluted state and the measurement time at setting be determined before the same constant mass flows of both media, the Operating condition of the heat exchanger correspond, are measured and from this the degree of contamination on the ratio of the mean logarithmic temperature differences and the enthalpy in the polluted and unpolluted state is determined. 2. The method according to item 1, characterized in that the mass flows of the media are set exactly to the design values. Field of application of the invention The invention can be used anywhere where shell-and-tube heat exchangers are used. Characteristic of the known state of the art When using tube bundle heat exchangers, contamination of the heating surfaces can occur. The determination of the contamination state is therefore of great importance for the operation of these heat exchangers. To determine the state of pollution, a number of methods and devices are already known. Thus, according to DD 217303, the heat exchanger can be operated with defined gaseous media and the degree of soiling can be determined as a function of the Reynolds number by measuring the pressure conditions. In DD 232749 the state of contamination is determined by means of a test specimen. DE 2547832 describes an arrangement for determining the degree of contamination in pipes of heat exchangers by means of a specially arranged test track. There is no known method with which the soiling state can be determined under operating conditions. All known methods and devices are sometimes subject to considerable technical effort, with special operating conditions and / or with erheblic'ien errors, so that a reliable determination of the state of contamination is not guaranteed. Object of the invention The aim of the invention is to determine the degree of contamination of Rohrbündelwärmeübertragern under operating conditions. Essence of the invention The object of the invention is to develop a method for determining the pollution Grai it of Rohrbündelwärmeübertragern with minimal technical effort. The above-described object is achieved according to the invention by setting the media flowing through the shell-and-tube heat exchanger to predetermined mass flows at the time of the measurements, it being favorable to select design values for them. The inlet and outlet temperatures of both media are first determined in the unpolluted condition and then at a desired measurement time. About the relationship _ At _m .A h "i, B - h'i.e can be calculated with the measured values of the degree of pollution, as the ratio of the heat transfer coefficients of the soiled and unpolluted state, where the degree of pollution
Al _n , the logarithmic temperature difference
hi the enthalpy of the mediumi
'the entry state the exit state
A the unpolluted condition
B the measuring time
represents