On-line fouling monitor for service water system heat exchangers

A combination sensing apparatus adapted for on-line monitoring of performance losses of a heat exchanger with respect to temperature and flow due to fouling of surfaces of said heat exchanger/heat exchanger comprising:

• a) heat exchanger apparatus comprising:
• i) a tube sheet having a plurality of heat transfer tubes;
• ii) an inlet header apparatus;
• and
• iii) a discharge apparatus;
• b) a plurality of dual tube and plug assemblies, each having a flow assembly tube and a temperature assembly tube wherein the flow assembly tube comprises a flow sensor for accurately measuring cooling water flow and a plug device for an attachment to a discharge end of the tube sheet, for measuring discharge water temperature;
• and the temperature assembly tube comprises a plurality of temperature sensors for detecting change of heat transfer resistance of a selected heat transfer tube comprising a pair of spaced apart probes;
• c) monitor means for comparing flow and discharge temperature signals from a selected first dual-tube device and for combining other flow and discharge temperature signals, from additional dual tube devices and connected to a microprocessor;
• and
• d) micro-processor means for utilizing inlet water temperature data provided by an inlet temperature sensor, for continuously calculating, recording and displaying the individual heat transfer tube heat transfer co-efficient employing the formula
• 1) Calculate flow rate for one tube,
• w.sub.1 =25*p*v*a
• 2) Calculate heat exchanged for one tube,
• q.sub.1 =w.sub.1 c.sub.p (t.sub.2 -t.sub.1)
• 3) Calculate total tube side flow,
• w=n*w.sub.1
• 4) Calculate total heat exchanged,
• Q=n*q.sub.1
• 5) Calculate shell side flow, ##EQU14## 6) Calculate log mean temperature difference (LMTD), ##EQU15## 7) Calculate measured overall heat transfer coefficient, ##EQU16## 8) Calculate fouling resistance, ##EQU17##

A method of monitoring fouling of inner surfaces of heat transfer tubes of a service water heat exchanger including a method to accurately measure change in heat transfer of the service water heat exchanger system as measured by change in heat transfer of actual individual heat transfer tubes within a heat exchanger while the heat exchanger is operational, comprising the steps of:

• a) providing a probe assembly without altering operating characteristics of said operating heat exchanger including:
• i) providing temperature sensor devices adapted for measuring efficiency of a heat exchanger which includes a plurality of temperature sensors;
• ii) providing flow sensor devices;
• and
• iii) providing a calculator for generating a signal representing the efficiency of the heat exchanger as reflected by change in conductivity of heat transfer tubes as computed by the formula;
• ##EQU18## b) detecting changes in heat transfer resistance of heat transfer tubes and a flow sensor for accurately measuring cooling water flow consisting of sensors attached to the discharge end of the heat exchanger and to a paddle wheel sensing device;
• c) combining flow and discharge temperature signals from a first dual-tube device, and combined with other flow and discharge temperature signals, from additional remotely spaced dual tube devices and comparing with clean conditions base line data;
• and
• d) transmitting flow and temperature signals are sent to a micro-processor which, utilizing inlet water temperature data provided by an inlet temperature sensors, continuously calculates, records and displays the individual heat transfer tube heat transfer co-efficient.