T-1100 Neutralisation and pH Correction — Winston Water Engineering

T-1100Neutralisation and pH Correction

pH is logarithmic, so the dose that moves you from 2 to 3 is ten times the dose that moves you from 3 to 4 — and near neutrality the curve goes vertical. That is why single-stage neutralisation oscillates and two-stage does not.

Cutaway — Neutralisation and pH Correction

WaterReagentNeutralised

How it works

Why it is hard — pH is a logarithm of concentration. Between pH 2 and 3 you are neutralising ninety per cent of the acid; between 6 and 7 you are neutralising almost nothing. The same dose has wildly different effect depending on where you are on the curve.
The vertical bit — Near neutrality the titration curve is close to vertical. A dose that is a few per cent too large takes you from pH 6 straight past 7 to pH 10. The control valve then reverses, and the plant oscillates around the setpoint forever.
Staging — The answer is to split the job. The first stage does the coarse work — say pH 2.5 to 5 — where the curve is flat and forgiving. The second trims 5 to 7 with a much smaller reagent valve. Each stage then operates on a manageable part of the curve.
Residence time — The probe cannot read what has not mixed yet. Give each stage at least five minutes and enough agitation to be well mixed, or the controller is reacting to a measurement that does not represent the tank.
Choosing the reagent — Caustic soda is fully soluble and reacts instantly, so the loop responds the moment you dose. It makes almost no sludge. It is also the most expensive per equivalent and the most aggressive thing on the site — the cost is in handling it, not in buying it.
What governs it — Reagent quantity is simple stoichiometry and rarely the problem. Controllability is the problem — pull the stages down to one with a wide pH swing and watch the loop become impossible, no matter how good the valve is.

Design parameters

The panel opposite runs the same correlations as the T-1100 design sheet, so the animation and the calculator cannot disagree. Every parameter below is live — drag one and the picture responds.

Parameter	Unit	Default	Range
Reagent
Reagent		Caustic soda	7 options
An acidic feed needs a base; an alkaline feed needs an acid. Move the influent pH across 7 and the reagent switches with it. Equivalent weight sets the dose; what the reaction leaves behind sets the sludge bill.
Duty
Flow	m³/h	40	2 – 300
Influent pH	–	2.5	0.5 – 13
Target pH	–	7	5 – 9.5
Tank volume	m³	12	0.5 – 120
Reagent strength	% w/w	32	5 – 50
Stages	off	2	1 – 3

Open the full T-1100 design sheet for the other six inputs, all twenty-seven results with their envelopes, the six equations printed beside the numbers they produce, and a calculation record you can export and put in a design file.

Live parameters

Six of the twelve inputs the T-1100 design sheet takes.

Reagent

An acidic feed needs a base; an alkaline feed needs an acid. Move the influent pH across 7 and the reagent switches with it. Equivalent weight sets the dose; what the reaction leaves behind sets the sludge bill.

Duty

Flow 40 m³/h

Influent pH 2.5 –

Target pH 7 –

Tank volume 12 m³

Reagent strength 32 % w/w

Stages 2 off

You have an estimate. The design sheet is the justification.

This page sizes the unit on six variables and tells you whether the headline numbers land in range. That is enough to sketch with, and it stays free. What it will not do is survive a design review: it does not show you the equation behind any number, it checks the obvious limits rather than all of them, and there is nothing to file.

The T-1100 design sheet runs the same physics on twelve inputs, reports twenty-seven results against their envelopes, prints the six governing equations beside the numbers they produce, and exports the lot as a calculation record for the design file.