August 09, 2010

ISO - Standard OR Business - 2

In continuation to my previous post on the topic.....

2. Claims & Reality?

Now first on ISO claims itself that - ISO standards also serve to safeguard consumers, and users in general, of products and services - as well as to make their lives simpler. HOW???????????????

Safeguard consumers & users - How???? To understand this we will start from the first Clause of ISO manual which is related to SCOPE - Scope of coverage of activities under ISO. This is the biggest loophole & biggest problem in the entire ISO standard which is used as an escape route wherever troublesome processes are involved.


The classic example:

Why the Soft drink companies do not specify the presence of pesticides in their product and then why not they do specify the limit of these pesticides which has been already proved by many international organizations. This is very prominent especially in India due to local government regulations, but ISO do not work on local regulations - They claim to be “International Standards”. Don't forget that these companies are also certified by ISO for their Indian operations.

So the first learning or flaw is that for any one kind of product there should be an internationally acceptable quality parameters (If you claim to be an International Standard - else ISO is not required because each country is already having its own standards & therefore nobody requires another standard which do not ask for improvement to an international level and just try to sell you a certificate with which your business can fetch more money – I doubt this also because the image of ISO is so diluted that there is no credit or premium for it) e.g. for a toothpaste of non-fluoride nature it should not have already identified harmful ingredients beyond the prescribed limit.

The first difference is that ISO says – You specify the quality but how it can be true especially for consumer products. So for this category of FMCG etc the quality is not the content of the product in terms of purity but in my opinion it is the limit of harmful contents in the product, then only it can safeguard the customer.

The example – according to one report (I do not have any legal binding here – this is based on the reports published & broadcasted in newspapers & TV channels), one of the government agency found the objectionable content in cold drinks of two world famous companies (everybody knows them) in India beyond the prescribed limit.

Even if we assume that it was qualifying local standards (Indian in this case) then how can ISO allow manufacturing a product for which WHO or any other world / international organization has set a different limit as harmful content? If it is so, then ISO is not an international standard OR I can say not following international standard.

One may argue that ISO is not setting quality of product its basically setting the quality standard for processes. OK then I must say they should not claim – “ISO standards also serve to safeguard consumers and users in general” the first line of their claim.

In fact, no activity of ISO can be related to safeguarding the interest of consumers, business partners, employees etc. I will put some example for them in the next few posts one by one. Yes, they have only one interest by partnering with some of the foreign business groups, who will ask manufacturers of any third world country to have ISO to qualify as their standard supplier. This way they put cost pressure on developing countries & simultaneously providing business to ISO.

Learning -1 Each product should have internationally specified limits for each harmful content which should be essentially written on the product. This should be the first condition of having ISO in any country any region on this globe.



Disclaimer - This is a series of my personal views on ISO systems, its implementation, Effectiveness etc. They do not carry any legal issue related to my personal views under the human right of "Freedom of Speech".

Get Free Updates:
*Please click on the confirmation link sent in your Spam folder of Email*

Continue to read this post...

July 26, 2010

ISO - Standard OR Business - 1

I am going to write a series on ISO system, its implementation practices, effectiveness, it's claims etc. in several parts in the form of a series. Anyone can put their frank opinion & comments on these write ups. We are not going to comment on ISO as organization but we are commenting on the systems, its effectiveness & industries which are implementing it.

Again this is not for criticism of any agency or organization; it is my experience sharing on actual implementation & loop holes in the system & its effective implementation.

I will show - How the basic purpose of this standard is defeated by standard itself - And my real experience no standards management expert or ISO expert who is responsible for its implementation is concerned about it - even after accepting these problems
resistively.

For reality purpose, we are referring the website quotes or matter from ‘ISO’ website.


1. Why Standards Matter?

This is the first question, the official website of ISO present to us, in a very nice & surely positive manner. It is soon justified that without ISO systems the product quality, incompatibility, cost and, safety are compromised.

One better paragraph on site says that - "ISO standards contribute to making the development, manufacturing and supply of products and services more efficient, safer and cleaner. They make trade between countries easier and fairer. They provide governments with a technical base for health, safety and environmental legislation. They aid in transferring technology to developing countries. ISO standards also serve to safeguard consumers, and users in general, of products and services - as well as to make their lives simpler." (Source : ISO Website)

Read on further claims - "When things go well - for example, when systems, machinery and devices work well and safely - then it is because they conform to standards. And the organization responsible for many thousands of the standards which benefit society worldwide is ISO." (Source : ISO Website)

Yes, Standards do matter & definitely help in making processes efficient, safer & cleaner as claimed but the difference do not lie in making a "voluminous standard", it lies in actual implementation & practice. The way ISO is implemented is totally useless as standard itself provides ways & means to enjoy bypasses to the spirit of the standard.

Therefore, it is neither helpful in making processes efficient as some or the other way is available to bypass the system nor safer or cleaner. ( How - You will see it through examples in the next parts of this series - Be patient).

There is no health, safety & environment improvement by implementing ISO....In fact, it is creating more problems to the environment - by using more papers - more documents - more consumption of power due to late sitting of ISO staff in organization to complete the time targets - late sitting for preparing for audits - many formats but only one line on one paper sheet - etc. etc. etc....

Even though I am not saying ISO system is bad - Mind it I am repeating - I say, ISO system needs further improvements in terms of its effectiveness.

The first problem I see is - to allow the manufacturer to go selectively. We will discuss this in next part.....



Disclaimer - This is a series of my personal views on ISO systems, its implementation, Effectiveness etc. They do not carry any legal issue related to my personal views under the human right of "Freedom of Speech".

Get Free Updates:
*Please click on the confirmation link sent in your Spam folder of Email*

Continue to read this post...

July 12, 2010

MVR - Use it for Higher Benefits


In my last post, I mentioned some background about mechanical vapor re-compression.

In this post I am going to illustrate some benefits out of MVR system.

In general they must be seen as energy saving schemes in the current scenario of high energy costs in most of the processes. The need to recover or re-utilize energy is essential in thermal separation processes such as evaporations, distillation etc.

Following are the general options available in the industry out of which MVR is the most unutilized or neglected one while being the most efficient one.

1. Multi Effect evaporation (MEE)
2. Vapor re-compression
a. Thermal recompression
b. Mechanical recompression



I am not covering other options as they are well known as my focus here is to mainly emphasize on the benefits of MVR. However, for comparison purpose we will start with MEE only.

MEE
In a multi effect evaporation plant, the vapors produced in the first effect are utilized as the heating medium of the second effect and so on. This effectively reduces steam consumption in proportion to the number of effects. Ideally unit mass of vapor on condensation can evaporate unit mass of liquid. The vapors generated at the first effect are condensed in the second stage to further evaporate the liquid from the second stage and so on. A temperature gradient of about 7-10°C is maintained between stages for maximum efficiency.

So a triple effect evaporator would consume only 35-36% of the energy in comparison to a single effect system. Thus for each kg of steam input to first effect we can theoretically produce 3 kg of evaporation, practically it would be as below because of efficiency of evaporation in the subsequent systems. So let us work on some nos.

The efficiency of 95% is assumed in all evaporation systems through out this comparison

Feed to first effect (say) – 1 Kg steam
The evaporation from first effect – 0.95 Kg steam
The evaporation from second effect – 0.90 Kg steam (i.e. 0.95 x 0.95)
The evaporation from third effect – 0.86 Kg steam (i.e. 0.90 x 0.95)

So total evaporation possible in a 3 stage MEE is = 0.95+0.90+0.86 = 2.71

This is generally the overall economy ratio of a 3stage MEE system. This means for every kg of live steam fed to the system you can remove 2.71 kg of water from the MEE system. Thus, the so called COP is 2.71.

Thermal recompression
Now let us see thermal recompression system which is nothing but an ejector system which boosts the pressure of first effect evaporation by using higher pressure steam so that it can be utilized in the next effect. The major difference is that it requires high pressure steam to elevate the pressure of evaporated steam and may or may not require pressure gradient in the system which is essential in MEE.

Initially, heating steam is used to initialize evaporation. The vapors evaporated are compressed to higher pressure and temperature by steam jet ejector, condensed back for heat recovery and the residual vapors are taken to second stage for condensation / heat recovery. The amount of surplus energy contained in the residual vapor corresponds to the amount of energy supplied for steam jet ejector operation. This is taken as additional heat input / work done for recovery of large heat content of the evaporated vapors

So by theory practically the economy ratio is 1 for thermal compression system as whatever energy we put into the system in terms of motive steam is recovered back in the condenser of the next stage.


MVR
So now it’s a turn of MVR system. The process is that the initial vaporization is done using steam or electrical heater to initiate the process & then system may balance itself if you run only one stage of evaporation (by inherent nature of the process & economy ratio you do not need more than one stage practically unless there is a huge requirement or some mechanical issue is involved). So let us now see the calculations.

Every kg of steam initiated from the system is already having its latent heat. Let us assume that the process is near atmospheric condition. So the latent heat is ~2257 KJ/Kg at 100 C & 1 bar.

Now this steam is taken by the compressor & compressed to bit higher pressure. The energy required for compression is given as electrical energy which is increased by the efficiency terms over & above the theoretical requirement. This compression energy depends on pressure ratio. Generally MVR are currently designed to a pressure ratio limit of 1.5. So if the compressor is increasing the pressure to say 1.5 bar then the work done by compressor is

W = (P2 – P1) x Vs x 100

W = specific work done = KJ/Kg
P2 = final pressure = 1.5 bar
P1 = initial pressure = 1.0 bar
Vs = specific volume of steam = 1.67 M3/Kg

So the energy required is

W = (1.5 -1.0) x 100 x 1.67 = 83.5 KJ/Kg

Now let us assume overall efficiency of compression process including electrical, transmission efficiencies is 60%. Then total actual energy requirement is

W = 83.5/0.6 = 139 KJ/Kg

This means by putting an energy of 139 KJ/Kg, we can recover the latent heat of 2257 KJ/Kg out of steam. Therefore by definition of COP of the process, it is

COP = 2257 / 139 = 16.2

This means that one stage of MVR is equal to 16 stages of MEE in terms of energy efficiency. This also means that energy equal to one kg of steam put into an MVR will or can evaporate 16 Kg of steam from the system.

Benefits
Now in terms of cost of energy, theoretically the power cost is double than steam cost. So effectively the ratio will be 16.2/2 = 8. Thus, effectively the operation cost can be reduced by 8 times in comparison to MEE or any other option.

Following are the other advantages

  1. Low specific energy consumption i.e. energy consumed per kg of product.

  2. Unmatched Higher Performance co-efficient i.e. the overall economy of the operation.

  3. Gentle evaporation of the product due to low temperature differences and hence useful for temperature sensitive operation. In fact it is never a problem for any material because it operates only at very low delta T.

  4. No load or reduced load on cooling towers as there is no CW condenser in the system.

  5. Simplicity of process, operation & maintenance.












Get Free Updates:
*Please click on the confirmation link sent in your Spam folder of Email*

Continue to read this post...

June 29, 2010

Mechanical Vapor Re-Compression

You may have seen the term Mechanical vapor compression or re-compression. It is basically the compression of vapors. The main difference is the general compression is used for gases not for vapors while this term is used for compression of vapors.

You know the difference in VAPOR & GAS...I am not going to cover it here.

The term is derived mainly from the compression of steam evaporated from the evaporators. It seems that the need got generated from the large scale desalination plants where very large amount of water is to be evaporated economically. So some brilliant chemical / mechanical engineer (I don't know him) thought about the use of some compression device so that evaporated steam it self can be used for heating purpose. It can be visualized from the diagram below.





The short description of the process is as below.

1. Unheated wastewater is fed to the liquid vapor separation tank (1) and is heated to a boil by the electric heating element (6).

2. Recirculation pump begins circulating heated water through the main heat exchanger (2) and back into the separation tank (1).

3.Steam flows up through the mist pad (8) to inlet side of vapor compressor (4).

4.Compressed steam from vapor compressor (4) is forced through the steam side of main heat exchanger (3) giving up latent heat to the counter flowing water from the separation tank (1).

5.High temperature distillate flows out of the main heat exchanger (3) to feedstock heat exchanger (7) giving up sensible heat to feedstock wastewater.

6.Upon reaching steady state, cold feedstock wastewater is fed at a constant rate through the feedstock heat exchanger (7) to raise temperature before feeding to recirculation loop.

7.Concentrate is periodically discharged based on temperature, conductivity or time from separation tank (1) to concentrate tank (9) through residue pump (10).

Benefits of MVR
The beauty of MVR is that by putting in a fraction of energy into comprssor, we can recover entire latent heat of steam. Thus it can produce a COP of >15. Though it has got many limitations but the economy ratio of 15 (Simply understand it this way - that one MVR evaporator is equal to 15 Multi Effect Evaporators running on successive levels.)

I will try to show one practical example with calculations in the next post as & when I get some more time from my schedule.

Work On it NOW....

Get Free Updates:
*Please click on the confirmation link sent in your Spam folder of Email*

Continue to read this post...